<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:ba4cb4ff-2f61-4192-9692-cbaf8194000f,g:a7437bfe-5a6b-4d0e-b76d-bf6af37caa74-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.paalp.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="pagp-20231231.xsd#CONSOLIDATEDBALANCESHEETS"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_b0c9c612-1f95-41f3-9566-ba20c3555e02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_f4638874-2032-48fd-bae6-8c80538572e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_b0c9c612-1f95-41f3-9566-ba20c3555e02" xlink:to="loc_us-gaap_StatementTable_f4638874-2032-48fd-bae6-8c80538572e7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_40d0a296-0b4f-4826-badb-5c89549b2795" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_f4638874-2032-48fd-bae6-8c80538572e7" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_40d0a296-0b4f-4826-badb-5c89549b2795" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_40d0a296-0b4f-4826-badb-5c89549b2795_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_40d0a296-0b4f-4826-badb-5c89549b2795" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_40d0a296-0b4f-4826-badb-5c89549b2795_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_11271769-eb03-4f82-ad56-17d82c04d524" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_40d0a296-0b4f-4826-badb-5c89549b2795" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_11271769-eb03-4f82-ad56-17d82c04d524" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_3725d400-50ed-45f6-a49f-a5f9da21cbcd" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_11271769-eb03-4f82-ad56-17d82c04d524" xlink:to="loc_pagp_SharesClassAMember_3725d400-50ed-45f6-a49f-a5f9da21cbcd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_3991fbc3-b246-4162-8853-a85b18a6b841" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b0c9c612-1f95-41f3-9566-ba20c3555e02" xlink:to="loc_us-gaap_AssetsAbstract_3991fbc3-b246-4162-8853-a85b18a6b841" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_a365351a-06f7-481a-a0ec-5c1915449e91" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3991fbc3-b246-4162-8853-a85b18a6b841" xlink:to="loc_us-gaap_AssetsCurrentAbstract_a365351a-06f7-481a-a0ec-5c1915449e91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_0011905c-f1dd-4c69-abc9-03bf5ed71c70" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_a365351a-06f7-481a-a0ec-5c1915449e91" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_0011905c-f1dd-4c69-abc9-03bf5ed71c70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesNetCurrent_e0b6dde3-df3b-4512-be9d-3c8de94297d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivablesNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_a365351a-06f7-481a-a0ec-5c1915449e91" xlink:to="loc_us-gaap_ReceivablesNetCurrent_e0b6dde3-df3b-4512-be9d-3c8de94297d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_d8c36e13-2b00-44ec-8d14-d9bc06742583" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_a365351a-06f7-481a-a0ec-5c1915449e91" xlink:to="loc_us-gaap_InventoryNet_d8c36e13-2b00-44ec-8d14-d9bc06742583" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsCurrent_4309d2a1-5c99-4b80-858d-d6997314a97c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_a365351a-06f7-481a-a0ec-5c1915449e91" xlink:to="loc_us-gaap_OtherAssetsCurrent_4309d2a1-5c99-4b80-858d-d6997314a97c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_61027cb2-472a-4dd1-8d98-95c478b18f92" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_a365351a-06f7-481a-a0ec-5c1915449e91" xlink:to="loc_us-gaap_AssetsCurrent_61027cb2-472a-4dd1-8d98-95c478b18f92" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_191f0541-c71a-40aa-bf27-f93919c66b7b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3991fbc3-b246-4162-8853-a85b18a6b841" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_191f0541-c71a-40aa-bf27-f93919c66b7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_48ad8a7f-756b-42f3-97aa-e0f9af7e63f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3991fbc3-b246-4162-8853-a85b18a6b841" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_48ad8a7f-756b-42f3-97aa-e0f9af7e63f5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_4f96021e-eb34-4704-b576-11d815d00b43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3991fbc3-b246-4162-8853-a85b18a6b841" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_4f96021e-eb34-4704-b576-11d815d00b43" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3991fbc3-b246-4162-8853-a85b18a6b841" xlink:to="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_1cdefe45-e5fa-4b3f-a68e-21144ddceacf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:to="loc_us-gaap_EquityMethodInvestments_1cdefe45-e5fa-4b3f-a68e-21144ddceacf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ec9dc2e5-fa9b-46c4-bacb-e3bbd708ccee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ec9dc2e5-fa9b-46c4-bacb-e3bbd708ccee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_57ba602f-eedb-46ec-b857-c6de021461d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_57ba602f-eedb-46ec-b857-c6de021461d1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_Linefill_f050a119-9b54-4a84-8a98-381203bbc5d1" xlink:href="pagp-20231231.xsd#pagp_Linefill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:to="loc_pagp_Linefill_f050a119-9b54-4a84-8a98-381203bbc5d1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_75eb4e76-8080-4e1b-8234-6658663f964b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_75eb4e76-8080-4e1b-8234-6658663f964b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNoncurrent_5b537411-d1d2-43d6-b23a-9186618a2067" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:to="loc_us-gaap_InventoryNoncurrent_5b537411-d1d2-43d6-b23a-9186618a2067" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_26d5f849-5381-46cc-a525-ccbd714f0aee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_e06fbb56-b55e-4e68-a2be-37c28b239589" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_26d5f849-5381-46cc-a525-ccbd714f0aee" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_10518820-4c81-4aaa-b338-fb40d4316e96" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_3991fbc3-b246-4162-8853-a85b18a6b841" xlink:to="loc_us-gaap_Assets_10518820-4c81-4aaa-b338-fb40d4316e96" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7d1dc5fb-b213-4006-b114-eddf5fb425f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b0c9c612-1f95-41f3-9566-ba20c3555e02" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7d1dc5fb-b213-4006-b114-eddf5fb425f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_4c88a6f1-e3f9-4fd7-be3e-08d812c40676" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7d1dc5fb-b213-4006-b114-eddf5fb425f3" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_4c88a6f1-e3f9-4fd7-be3e-08d812c40676" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableTradeCurrent_2aadf938-39e6-41cf-8508-d8d04546ddd7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableTradeCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_4c88a6f1-e3f9-4fd7-be3e-08d812c40676" xlink:to="loc_us-gaap_AccountsPayableTradeCurrent_2aadf938-39e6-41cf-8508-d8d04546ddd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent_d3bdc511-2bcc-4f84-ae92-e651a9f8a163" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_4c88a6f1-e3f9-4fd7-be3e-08d812c40676" xlink:to="loc_us-gaap_DebtCurrent_d3bdc511-2bcc-4f84-ae92-e651a9f8a163" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_a4ec5f9b-0775-4549-8023-2549d90d5aa7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_4c88a6f1-e3f9-4fd7-be3e-08d812c40676" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_a4ec5f9b-0775-4549-8023-2549d90d5aa7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_fb67e24a-b031-432f-bfad-b28472420956" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_4c88a6f1-e3f9-4fd7-be3e-08d812c40676" xlink:to="loc_us-gaap_LiabilitiesCurrent_fb67e24a-b031-432f-bfad-b28472420956" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesNoncurrentAbstract_670d4fc0-aa2e-4b34-a744-79e6a22b864b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7d1dc5fb-b213-4006-b114-eddf5fb425f3" xlink:to="loc_us-gaap_LiabilitiesNoncurrentAbstract_670d4fc0-aa2e-4b34-a744-79e6a22b864b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorLongTermNotes_c537f0f9-38b9-44ca-abb2-a53acac3025c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorLongTermNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_670d4fc0-aa2e-4b34-a744-79e6a22b864b" xlink:to="loc_us-gaap_SeniorLongTermNotes_c537f0f9-38b9-44ca-abb2-a53acac3025c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLongTermDebtNoncurrent_3bd3d788-e621-4df6-8dc4-c66bf7312900" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_670d4fc0-aa2e-4b34-a744-79e6a22b864b" xlink:to="loc_us-gaap_OtherLongTermDebtNoncurrent_3bd3d788-e621-4df6-8dc4-c66bf7312900" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_ed1eb5f0-0d7f-45e8-af87-58171efe3e55" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_670d4fc0-aa2e-4b34-a744-79e6a22b864b" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_ed1eb5f0-0d7f-45e8-af87-58171efe3e55" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_3e27fb73-561a-485f-809c-16389b814602" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_670d4fc0-aa2e-4b34-a744-79e6a22b864b" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_3e27fb73-561a-485f-809c-16389b814602" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesNoncurrent_f02bde2e-5550-4be7-8ab1-9149f4bbdff2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesNoncurrentAbstract_670d4fc0-aa2e-4b34-a744-79e6a22b864b" xlink:to="loc_us-gaap_LiabilitiesNoncurrent_f02bde2e-5550-4be7-8ab1-9149f4bbdff2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_6afecef1-d062-4e4f-94e4-c34dc190bbc0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7d1dc5fb-b213-4006-b114-eddf5fb425f3" xlink:to="loc_us-gaap_CommitmentsAndContingencies_6afecef1-d062-4e4f-94e4-c34dc190bbc0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterestAbstract_02a57962-c1fd-46e5-8e92-da6e40de8d02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7d1dc5fb-b213-4006-b114-eddf5fb425f3" xlink:to="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterestAbstract_02a57962-c1fd-46e5-8e92-da6e40de8d02" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccount_c63598fc-29cd-428e-9210-376476381a28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterestAbstract_02a57962-c1fd-46e5-8e92-da6e40de8d02" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccount_c63598fc-29cd-428e-9210-376476381a28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAttributableToNoncontrollingInterest_84ff9d4b-8e7a-49d3-8a6e-d60a8be3c4d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterestAbstract_02a57962-c1fd-46e5-8e92-da6e40de8d02" xlink:to="loc_us-gaap_PartnersCapitalAttributableToNoncontrollingInterest_84ff9d4b-8e7a-49d3-8a6e-d60a8be3c4d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest_bb2c73af-8dbd-4ac2-a027-febd913e99a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterestAbstract_02a57962-c1fd-46e5-8e92-da6e40de8d02" xlink:to="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest_bb2c73af-8dbd-4ac2-a027-febd913e99a9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_82263c5f-cc67-4b5f-9d3f-a88cb0ddb0a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_7d1dc5fb-b213-4006-b114-eddf5fb425f3" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_82263c5f-cc67-4b5f-9d3f-a88cb0ddb0a6" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/CONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="simple" xlink:href="pagp-20231231.xsd#CONSOLIDATEDBALANCESHEETSParenthetical"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/CONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_688410dd-2e3b-4763-ad07-f65a6a2f1088" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_f0dba910-618d-4c42-8a56-aaf4bf0db75a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_688410dd-2e3b-4763-ad07-f65a6a2f1088" xlink:to="loc_us-gaap_StatementTable_f0dba910-618d-4c42-8a56-aaf4bf0db75a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_14f0035f-6340-47a2-9d92-5e487fac7818" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_f0dba910-618d-4c42-8a56-aaf4bf0db75a" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_14f0035f-6340-47a2-9d92-5e487fac7818" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_14f0035f-6340-47a2-9d92-5e487fac7818_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_14f0035f-6340-47a2-9d92-5e487fac7818" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_14f0035f-6340-47a2-9d92-5e487fac7818_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_de40b5a5-549d-4b24-bde4-68c67a48caad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_14f0035f-6340-47a2-9d92-5e487fac7818" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_de40b5a5-549d-4b24-bde4-68c67a48caad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_83465aba-63d2-41be-8a28-925e97b91569" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_de40b5a5-549d-4b24-bde4-68c67a48caad" xlink:to="loc_pagp_SharesClassAMember_83465aba-63d2-41be-8a28-925e97b91569" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding_617cd3a3-7943-4e3c-9f02-b427e3e97dfa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_688410dd-2e3b-4763-ad07-f65a6a2f1088" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding_617cd3a3-7943-4e3c-9f02-b427e3e97dfa" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="pagp-20231231.xsd#CONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_5fc8e0bd-6eed-44f5-8401-ea79567c0ab4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_StatementTable_5fc8e0bd-6eed-44f5-8401-ea79567c0ab4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_31adb239-1767-4da4-bc29-1dda6cd872a3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_5fc8e0bd-6eed-44f5-8401-ea79567c0ab4" xlink:to="loc_srt_ProductOrServiceAxis_31adb239-1767-4da4-bc29-1dda6cd872a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_31adb239-1767-4da4-bc29-1dda6cd872a3_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_31adb239-1767-4da4-bc29-1dda6cd872a3" xlink:to="loc_srt_ProductsAndServicesDomain_31adb239-1767-4da4-bc29-1dda6cd872a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_fc271def-7479-485c-a97e-cbe38176831d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_31adb239-1767-4da4-bc29-1dda6cd872a3" xlink:to="loc_srt_ProductsAndServicesDomain_fc271def-7479-485c-a97e-cbe38176831d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_1be6754a-5b48-4039-bb2d-eac986f8e011" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_fc271def-7479-485c-a97e-cbe38176831d" xlink:to="loc_us-gaap_ProductMember_1be6754a-5b48-4039-bb2d-eac986f8e011" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_33090ff6-ce92-4aa8-baa0-e5cc8876e8d3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_fc271def-7479-485c-a97e-cbe38176831d" xlink:to="loc_us-gaap_ServiceMember_33090ff6-ce92-4aa8-baa0-e5cc8876e8d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_e3c6f121-7d4a-4016-ad6f-9ca8a0490112" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_5fc8e0bd-6eed-44f5-8401-ea79567c0ab4" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_e3c6f121-7d4a-4016-ad6f-9ca8a0490112" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_e3c6f121-7d4a-4016-ad6f-9ca8a0490112_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_e3c6f121-7d4a-4016-ad6f-9ca8a0490112" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_e3c6f121-7d4a-4016-ad6f-9ca8a0490112_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_ba42280b-021c-440c-be73-36c798994ae6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_e3c6f121-7d4a-4016-ad6f-9ca8a0490112" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_ba42280b-021c-440c-be73-36c798994ae6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_9f77cfec-be79-474c-8dc0-28fb5818536d" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_ba42280b-021c-440c-be73-36c798994ae6" xlink:to="loc_pagp_SharesClassAMember_9f77cfec-be79-474c-8dc0-28fb5818536d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_661db214-2a9d-438f-99b4-4c36ef3bf8b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_RevenuesAbstract_661db214-2a9d-438f-99b4-4c36ef3bf8b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_9ab11025-6706-424f-90ec-a2ca48e84bf8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_661db214-2a9d-438f-99b4-4c36ef3bf8b0" xlink:to="loc_us-gaap_Revenues_9ab11025-6706-424f-90ec-a2ca48e84bf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_f31359d9-22df-4951-9bd8-6a32da6f268e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_f31359d9-22df-4951-9bd8-6a32da6f268e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_5fc24319-3a7a-4cd2-9390-2d14c3956ec4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_f31359d9-22df-4951-9bd8-6a32da6f268e" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_5fc24319-3a7a-4cd2-9390-2d14c3956ec4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingCostsAndExpenses_daf4e2a4-3a36-46f1-abfd-2fbb6522b3fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingCostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_f31359d9-22df-4951-9bd8-6a32da6f268e" xlink:to="loc_us-gaap_OperatingCostsAndExpenses_daf4e2a4-3a36-46f1-abfd-2fbb6522b3fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_36ed26e4-021d-4368-b80e-fa8651d8b953" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_f31359d9-22df-4951-9bd8-6a32da6f268e" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_36ed26e4-021d-4368-b80e-fa8651d8b953" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_9b589700-455a-4c85-be38-8e387a1c6cf9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_f31359d9-22df-4951-9bd8-6a32da6f268e" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_9b589700-455a-4c85-be38-8e387a1c6cf9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_89f72bfa-dad9-46b8-9a24-2cbc1e9fbf9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_f31359d9-22df-4951-9bd8-6a32da6f268e" xlink:to="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_89f72bfa-dad9-46b8-9a24-2cbc1e9fbf9f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_9bf3c81a-0610-479c-a352-fc0a0d989627" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_f31359d9-22df-4951-9bd8-6a32da6f268e" xlink:to="loc_us-gaap_CostsAndExpenses_9bf3c81a-0610-479c-a352-fc0a0d989627" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_333a1cf9-0885-4c5c-824c-7c2134ab134f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_OperatingIncomeLoss_333a1cf9-0885-4c5c-824c-7c2134ab134f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_5b66bfa6-49de-4664-a1eb-503f9b25635f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonoperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_5b66bfa6-49de-4664-a1eb-503f9b25635f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_9edf1aa2-2bb0-463a-b112-781287ea12f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_5b66bfa6-49de-4664-a1eb-503f9b25635f" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_9edf1aa2-2bb0-463a-b112-781287ea12f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet_604ca445-b91a-40a9-b248-ee8096206ebb" xlink:href="pagp-20231231.xsd#pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_5b66bfa6-49de-4664-a1eb-503f9b25635f" xlink:to="loc_pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet_604ca445-b91a-40a9-b248-ee8096206ebb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_9edec73c-e875-4d4b-bcd0-3112a9ea4be2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_5b66bfa6-49de-4664-a1eb-503f9b25635f" xlink:to="loc_us-gaap_InterestExpense_9edec73c-e875-4d4b-bcd0-3112a9ea4be2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_6b61788e-4a9a-4622-9165-e2881cab0044" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_5b66bfa6-49de-4664-a1eb-503f9b25635f" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_6b61788e-4a9a-4622-9165-e2881cab0044" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e1951980-6bbc-48bf-8050-18c1e8fb64fb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e1951980-6bbc-48bf-8050-18c1e8fb64fb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_bb80762a-797f-4bfc-966f-fddd6ac3f2d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_bb80762a-797f-4bfc-966f-fddd6ac3f2d1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_03aabfea-4f9c-443d-b0b1-bb21c4b0333e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_03aabfea-4f9c-443d-b0b1-bb21c4b0333e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_91e7633b-2174-4ef2-bd1e-28abbdc97da2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_ProfitLoss_91e7633b-2174-4ef2-bd1e-28abbdc97da2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_2a02a060-0ee3-4f65-a498-4f3b7819b065" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_2a02a060-0ee3-4f65-a498-4f3b7819b065" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_5a6ebaaf-e85e-4e78-9c76-fb196f872a17" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_NetIncomeLoss_5a6ebaaf-e85e-4e78-9c76-fb196f872a17" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_50ce8381-d1bc-4783-b17f-ab0134d31bfb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_50ce8381-d1bc-4783-b17f-ab0134d31bfb" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_7843a91f-c15b-461e-92ed-1dc52fbea7d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_7843a91f-c15b-461e-92ed-1dc52fbea7d8" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_ed702204-3b4b-4e3e-b47a-4e3301ae6781" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_EarningsPerShareBasic_ed702204-3b4b-4e3e-b47a-4e3301ae6781" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_71a9befd-3e43-4832-8969-2c6ce90c4871" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b848e4bb-e337-49f1-b75a-f94c80233f53" xlink:to="loc_us-gaap_EarningsPerShareDiluted_71a9befd-3e43-4832-8969-2c6ce90c4871" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSS" xlink:type="simple" xlink:href="pagp-20231231.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSS"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_047b23ab-a04e-4d70-ab47-1449f616745f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_c4934ca8-51d4-47db-8431-fe4fdc3084f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_047b23ab-a04e-4d70-ab47-1449f616745f" xlink:to="loc_us-gaap_StatementTable_c4934ca8-51d4-47db-8431-fe4fdc3084f2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsAxis_03145230-9151-4dfc-af0b-2aa3a633dee8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_c4934ca8-51d4-47db-8431-fe4fdc3084f2" xlink:to="loc_us-gaap_PartnerCapitalComponentsAxis_03145230-9151-4dfc-af0b-2aa3a633dee8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_03145230-9151-4dfc-af0b-2aa3a633dee8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_03145230-9151-4dfc-af0b-2aa3a633dee8" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_03145230-9151-4dfc-af0b-2aa3a633dee8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_024a48ed-b8c0-4c3b-8eaa-8ac2feb4f647" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_03145230-9151-4dfc-af0b-2aa3a633dee8" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_024a48ed-b8c0-4c3b-8eaa-8ac2feb4f647" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember_9e827b72-b260-48e6-922d-217ae9548ada" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_024a48ed-b8c0-4c3b-8eaa-8ac2feb4f647" xlink:to="loc_us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember_9e827b72-b260-48e6-922d-217ae9548ada" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_06de6e48-e7cb-4e86-9724-5f6df67e6fb5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_024a48ed-b8c0-4c3b-8eaa-8ac2feb4f647" xlink:to="loc_us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_06de6e48-e7cb-4e86-9724-5f6df67e6fb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AOCIOtherIncludingPortionAttributabletoNoncontrollingInterestMember_de0f8789-462d-4ac3-ac3e-4e1f05ec8b7b" xlink:href="pagp-20231231.xsd#pagp_AOCIOtherIncludingPortionAttributabletoNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_024a48ed-b8c0-4c3b-8eaa-8ac2feb4f647" xlink:to="loc_pagp_AOCIOtherIncludingPortionAttributabletoNoncontrollingInterestMember_de0f8789-462d-4ac3-ac3e-4e1f05ec8b7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_affdfc9d-58c7-4264-aec5-566ac58b2a22" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_024a48ed-b8c0-4c3b-8eaa-8ac2feb4f647" xlink:to="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_affdfc9d-58c7-4264-aec5-566ac58b2a22" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_ee869ea4-bd58-4b3e-ab7a-b37e4a341663" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047b23ab-a04e-4d70-ab47-1449f616745f" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_ee869ea4-bd58-4b3e-ab7a-b37e4a341663" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest_d903ebed-75b6-4e4b-abce-4b75a7f018b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_ee869ea4-bd58-4b3e-ab7a-b37e4a341663" xlink:to="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest_d903ebed-75b6-4e4b-abce-4b75a7f018b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_39d78272-34a0-454f-8e13-29834d38d802" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_ee869ea4-bd58-4b3e-ab7a-b37e4a341663" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_39d78272-34a0-454f-8e13-29834d38d802" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_d8157895-3cb9-46ff-9592-67c77de07115" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_ee869ea4-bd58-4b3e-ab7a-b37e4a341663" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_d8157895-3cb9-46ff-9592-67c77de07115" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_c6d56de0-bf6e-4a62-9a94-fb170bfd7d05" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_ee869ea4-bd58-4b3e-ab7a-b37e4a341663" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_c6d56de0-bf6e-4a62-9a94-fb170bfd7d05" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeOtherNetOfTax_94cd5ad7-9c9c-46d4-be28-473614e6257a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeOtherNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_ee869ea4-bd58-4b3e-ab7a-b37e4a341663" xlink:to="loc_us-gaap_OtherComprehensiveIncomeOtherNetOfTax_94cd5ad7-9c9c-46d4-be28-473614e6257a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_bf0b2eea-8a39-43d7-bd0a-fe2a96b6c1a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_ee869ea4-bd58-4b3e-ab7a-b37e4a341663" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_bf0b2eea-8a39-43d7-bd0a-fe2a96b6c1a0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest_f11fa1c7-50bb-4608-b4c4-f92c13af3820" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="simple" xlink:href="pagp-20231231.xsd#CONSOLIDATEDSTATEMENTSOFCASHFLOWS"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_2fc6bca7-7a3f-4021-b257-2c699c38a784" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:to="loc_us-gaap_StatementTable_2fc6bca7-7a3f-4021-b257-2c699c38a784" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_b97fd8f6-5bac-4207-9357-00bfcb3a4a00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2fc6bca7-7a3f-4021-b257-2c699c38a784" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_b97fd8f6-5bac-4207-9357-00bfcb3a4a00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_b97fd8f6-5bac-4207-9357-00bfcb3a4a00_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_b97fd8f6-5bac-4207-9357-00bfcb3a4a00" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_b97fd8f6-5bac-4207-9357-00bfcb3a4a00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_2461972e-3c8f-4665-b206-fc2a717af8a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_b97fd8f6-5bac-4207-9357-00bfcb3a4a00" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_2461972e-3c8f-4665-b206-fc2a717af8a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_a20fac53-aa7f-4ae3-9ca2-0eec32eb8a19" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_2461972e-3c8f-4665-b206-fc2a717af8a3" xlink:to="loc_us-gaap_NoncontrollingInterestMember_a20fac53-aa7f-4ae3-9ca2-0eec32eb8a19" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract_a64cff82-3237-40bf-ad07-559a51b75aec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract_a64cff82-3237-40bf-ad07-559a51b75aec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_9b316bb2-bf53-413b-97be-673a97c98c43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract_a64cff82-3237-40bf-ad07-559a51b75aec" xlink:to="loc_us-gaap_ProfitLoss_9b316bb2-bf53-413b-97be-673a97c98c43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract_a64cff82-3237-40bf-ad07-559a51b75aec" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_4cb003fe-308c-4764-b878-fbc6938c7d51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_4cb003fe-308c-4764-b878-fbc6938c7d51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_7f972bc6-2013-4b6d-be43-fcaf28b7a2eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_7f972bc6-2013-4b6d-be43-fcaf28b7a2eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_2e7bff01-cc3e-4399-bfa8-52a14e35c1cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_2e7bff01-cc3e-4399-bfa8-52a14e35c1cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_702335b4-3d60-475f-8c6c-257daf75acee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_702335b4-3d60-475f-8c6c-257daf75acee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainLossOnSalesOfLinefill_9da8cb31-8aed-424c-be9a-b1856044db2c" xlink:href="pagp-20231231.xsd#pagp_GainLossOnSalesOfLinefill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_pagp_GainLossOnSalesOfLinefill_9da8cb31-8aed-424c-be9a-b1856044db2c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_ebb63e66-f4a1-4dfc-a453-61309a113c9e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_ebb63e66-f4a1-4dfc-a453-61309a113c9e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NetCashPaidReceivedforTerminatedHedgingInstruments_ed8408ee-fdc0-4076-bba0-9ce270f9a3d8" xlink:href="pagp-20231231.xsd#pagp_NetCashPaidReceivedforTerminatedHedgingInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_pagp_NetCashPaidReceivedforTerminatedHedgingInstruments_ed8408ee-fdc0-4076-bba0-9ce270f9a3d8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet_ca5bc230-dfc7-4afc-a7f6-75a265e5ffb1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet_ca5bc230-dfc7-4afc-a7f6-75a265e5ffb1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_82a255dd-06b3-4e15-8e14-4c57ed43ed14" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_82a255dd-06b3-4e15-8e14-4c57ed43ed14" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_9e921bf0-77fe-4e98-b438-ca7d2d89898d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentDividendsOrDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_9e921bf0-77fe-4e98-b438-ca7d2d89898d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet_d7d9a62d-a56d-4696-bc4f-4a97b275ce4d" xlink:href="pagp-20231231.xsd#pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet_d7d9a62d-a56d-4696-bc4f-4a97b275ce4d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_f5bbf596-f344-4ece-b917-03b1680b1606" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncashIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_f5bbf596-f344-4ece-b917-03b1680b1606" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_49c2a0dc-17c3-4bd5-b2f1-9a4de376b5f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_49c2a0dc-17c3-4bd5-b2f1-9a4de376b5f6" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsAndOtherReceivables_aff45f79-5bdd-43a9-898e-44e882bb484e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsAndOtherReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_49c2a0dc-17c3-4bd5-b2f1-9a4de376b5f6" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsAndOtherReceivables_aff45f79-5bdd-43a9-898e-44e882bb484e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_23a28c3a-2997-4a15-83c4-0995dd9f5ff9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_49c2a0dc-17c3-4bd5-b2f1-9a4de376b5f6" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_23a28c3a-2997-4a15-83c4-0995dd9f5ff9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_c828016a-d18d-4c4f-a146-e712c4b626ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_49c2a0dc-17c3-4bd5-b2f1-9a4de376b5f6" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_c828016a-d18d-4c4f-a146-e712c4b626ef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_f4e650a2-edb5-4d22-857c-3c15031d95e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8247c69a-55e3-4008-bb04-cd15d73befa5" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_f4e650a2-edb5-4d22-857c-3c15031d95e6" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesAndInterestInAffiliates_b0b26577-315a-41cb-ab17-f2649643b0d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesAndInterestInAffiliates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesAndInterestInAffiliates_b0b26577-315a-41cb-ab17-f2649643b0d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CapitalContributionsToEquityMethodInvestees_3dca1aa5-ec17-47e6-9b6c-58e5365acdee" xlink:href="pagp-20231231.xsd#pagp_CapitalContributionsToEquityMethodInvestees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:to="loc_pagp_CapitalContributionsToEquityMethodInvestees_3dca1aa5-ec17-47e6-9b6c-58e5365acdee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_889ad405-61a2-4a00-97b1-62d2d7d20feb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_889ad405-61a2-4a00-97b1-62d2d7d20feb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CashPaidRelatedToPurchasesOfLinefill_0d0fe7d4-eff8-4cc5-aa47-e36ffd4e03e8" xlink:href="pagp-20231231.xsd#pagp_CashPaidRelatedToPurchasesOfLinefill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:to="loc_pagp_CashPaidRelatedToPurchasesOfLinefill_0d0fe7d4-eff8-4cc5-aa47-e36ffd4e03e8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfProductiveAssets_7d579c96-9189-4e98-99ce-1ce58f8c9600" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleOfProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:to="loc_us-gaap_ProceedsFromSaleOfProductiveAssets_7d579c96-9189-4e98-99ce-1ce58f8c9600" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CashReceivedRelatedToSalesOfLinefill_f7ccdd61-626e-4439-a16a-98ae9989ec62" xlink:href="pagp-20231231.xsd#pagp_CashReceivedRelatedToSalesOfLinefill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:to="loc_pagp_CashReceivedRelatedToSalesOfLinefill_f7ccdd61-626e-4439-a16a-98ae9989ec62" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_36c612c1-bc68-4ae6-aff9-adbfec52970d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:to="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_36c612c1-bc68-4ae6-aff9-adbfec52970d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_12c6fbd4-5f25-4214-b54c-83b2285628ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_78322d9b-d2df-4ed6-b477-251e6f522828" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_12c6fbd4-5f25-4214-b54c-83b2285628ba" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromRepaymentsOfCommercialPaper_b856d03f-1e69-43e4-8263-2246031488ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromRepaymentsOfCommercialPaper"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_ProceedsFromRepaymentsOfCommercialPaper_b856d03f-1e69-43e4-8263-2246031488ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NetProceedsFromRepaymentsOfHedgedInventoryFacility_58a0a6e6-49fa-457a-a1f4-d45cd90045d4" xlink:href="pagp-20231231.xsd#pagp_NetProceedsFromRepaymentsOfHedgedInventoryFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_pagp_NetProceedsFromRepaymentsOfHedgedInventoryFacility_58a0a6e6-49fa-457a-a1f4-d45cd90045d4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSecuredDebt_bb8c6b57-c9de-4e1d-b54b-3c34c775e47c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfSecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_RepaymentsOfSecuredDebt_bb8c6b57-c9de-4e1d-b54b-3c34c775e47c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSeniorDebt_2ec470ae-1840-4f2d-9ce2-de9fd0cb2d4c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_RepaymentsOfSeniorDebt_2ec470ae-1840-4f2d-9ce2-de9fd0cb2d4c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToMinorityShareholders_a1bc0bcc-9641-4d72-88e2-d3dc31755b31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToMinorityShareholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_PaymentsToMinorityShareholders_a1bc0bcc-9641-4d72-88e2-d3dc31755b31" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionMadeToLimitedPartnerCashDistributionsPaid_d1e7c43a-3d2d-4ca7-96f7-86c5df950520" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionMadeToLimitedPartnerCashDistributionsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_DistributionMadeToLimitedPartnerCashDistributionsPaid_d1e7c43a-3d2d-4ca7-96f7-86c5df950520" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsMinorityInterest_51cebc91-1666-448e-a1d7-faab44bbcad9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsOfDividendsMinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_PaymentsOfDividendsMinorityInterest_51cebc91-1666-448e-a1d7-faab44bbcad9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromMinorityShareholders_4f1e1979-e6fb-4e9f-be9c-ec56590b335c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromMinorityShareholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_ProceedsFromMinorityShareholders_4f1e1979-e6fb-4e9f-be9c-ec56590b335c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_71a1d4cc-fe16-4b42-8c4b-6fe7d9ca2f3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_71a1d4cc-fe16-4b42-8c4b-6fe7d9ca2f3e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_09f6a5c7-2935-41c7-8910-24c04fd3e4c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_6830297f-6424-49ec-aa07-3e6e11cb05ac" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_09f6a5c7-2935-41c7-8910-24c04fd3e4c6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_75590b22-a9b4-4c52-b5f8-9439cd5e4b82" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_75590b22-a9b4-4c52-b5f8-9439cd5e4b82" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_93a3e8bb-39f6-4950-a96e-cb9dc0130cdc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_93a3e8bb-39f6-4950-a96e-cb9dc0130cdc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_3fbd6cee-bd9a-4d0e-9553-5cc20e7779f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_3fbd6cee-bd9a-4d0e-9553-5cc20e7779f0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_a3bdd12e-3232-476c-881e-5f79fa409614" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_46cafbaf-4843-4b16-a6a9-f2934c7721b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ea5c204f-bc3f-4a2a-845d-fc16d88e52eb" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_46cafbaf-4843-4b16-a6a9-f2934c7721b6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_0b841b0f-7019-4200-a241-f12ab9332ff4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_46cafbaf-4843-4b16-a6a9-f2934c7721b6" xlink:to="loc_us-gaap_InterestPaidNet_0b841b0f-7019-4200-a241-f12ab9332ff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_81a7126c-15b9-4742-942f-6826e2e8a9db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_46cafbaf-4843-4b16-a6a9-f2934c7721b6" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_81a7126c-15b9-4742-942f-6826e2e8a9db" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINPARTNERSCAPITAL" xlink:type="simple" xlink:href="pagp-20231231.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINPARTNERSCAPITAL"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINPARTNERSCAPITAL" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_3bea35a2-635c-4902-a096-6da02b5b3ce2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_ba294a85-0590-4c68-bc81-8946191d7c73" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_3bea35a2-635c-4902-a096-6da02b5b3ce2" xlink:to="loc_us-gaap_StatementTable_ba294a85-0590-4c68-bc81-8946191d7c73" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_1195c0c9-4828-4c9e-9802-f6d163d92958" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_ba294a85-0590-4c68-bc81-8946191d7c73" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_1195c0c9-4828-4c9e-9802-f6d163d92958" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_1195c0c9-4828-4c9e-9802-f6d163d92958_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_1195c0c9-4828-4c9e-9802-f6d163d92958" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_1195c0c9-4828-4c9e-9802-f6d163d92958_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_985e04a1-da56-40d3-88c1-aa9884d7e63d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_1195c0c9-4828-4c9e-9802-f6d163d92958" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_985e04a1-da56-40d3-88c1-aa9884d7e63d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnerMember_9b4f1ffa-412b-4c18-a547-cbe4cd2c9d74" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_985e04a1-da56-40d3-88c1-aa9884d7e63d" xlink:to="loc_us-gaap_LimitedPartnerMember_9b4f1ffa-412b-4c18-a547-cbe4cd2c9d74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_51062f23-3618-4ece-b4e9-eeec45389f30" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_ba294a85-0590-4c68-bc81-8946191d7c73" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_51062f23-3618-4ece-b4e9-eeec45389f30" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_51062f23-3618-4ece-b4e9-eeec45389f30_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_51062f23-3618-4ece-b4e9-eeec45389f30" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_51062f23-3618-4ece-b4e9-eeec45389f30_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_3e69d1a8-342a-4db5-aa67-b1d6625ced7b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_51062f23-3618-4ece-b4e9-eeec45389f30" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_3e69d1a8-342a-4db5-aa67-b1d6625ced7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_5b76792b-7674-4537-ae0f-aa41df1b872e" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_3e69d1a8-342a-4db5-aa67-b1d6625ced7b" xlink:to="loc_pagp_SharesClassAMember_5b76792b-7674-4537-ae0f-aa41df1b872e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsAxis_109c7eb3-140b-4b2d-bc7f-93c3a485acee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_ba294a85-0590-4c68-bc81-8946191d7c73" xlink:to="loc_us-gaap_PartnerCapitalComponentsAxis_109c7eb3-140b-4b2d-bc7f-93c3a485acee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_109c7eb3-140b-4b2d-bc7f-93c3a485acee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_109c7eb3-140b-4b2d-bc7f-93c3a485acee" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_109c7eb3-140b-4b2d-bc7f-93c3a485acee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_35b31ba6-9429-43a0-9630-ffa05d9d66be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_109c7eb3-140b-4b2d-bc7f-93c3a485acee" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_35b31ba6-9429-43a0-9630-ffa05d9d66be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_972f98ed-ed44-485e-95c5-3915ab28e3ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_35b31ba6-9429-43a0-9630-ffa05d9d66be" xlink:to="loc_us-gaap_ParentMember_972f98ed-ed44-485e-95c5-3915ab28e3ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_a8112f87-8e00-4519-8cfa-4b019cca1536" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_35b31ba6-9429-43a0-9630-ffa05d9d66be" xlink:to="loc_us-gaap_NoncontrollingInterestMember_a8112f87-8e00-4519-8cfa-4b019cca1536" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_1351187b-38eb-462c-ab26-009d97434a09" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_ba294a85-0590-4c68-bc81-8946191d7c73" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_1351187b-38eb-462c-ab26-009d97434a09" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1351187b-38eb-462c-ab26-009d97434a09_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_1351187b-38eb-462c-ab26-009d97434a09" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1351187b-38eb-462c-ab26-009d97434a09_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f8b5846d-b733-45fe-b08e-0a5b62eba1ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_1351187b-38eb-462c-ab26-009d97434a09" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f8b5846d-b733-45fe-b08e-0a5b62eba1ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_e539a8eb-9596-450a-9848-beed04b60401" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f8b5846d-b733-45fe-b08e-0a5b62eba1ff" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_e539a8eb-9596-450a-9848-beed04b60401" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_f1f31c6e-2338-41f3-8ca6-276bb5378121" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f8b5846d-b733-45fe-b08e-0a5b62eba1ff" xlink:to="loc_pagp_CactusIIPipelineLLCMember_f1f31c6e-2338-41f3-8ca6-276bb5378121" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_b468c535-6061-45bf-b727-e1fad92616f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_ba294a85-0590-4c68-bc81-8946191d7c73" xlink:to="loc_us-gaap_TransactionTypeAxis_b468c535-6061-45bf-b727-e1fad92616f0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_b468c535-6061-45bf-b727-e1fad92616f0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_b468c535-6061-45bf-b727-e1fad92616f0" xlink:to="loc_us-gaap_TransactionDomain_b468c535-6061-45bf-b727-e1fad92616f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_d582b53b-1acc-41c2-b806-58883b0d6c10" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_b468c535-6061-45bf-b727-e1fad92616f0" xlink:to="loc_us-gaap_TransactionDomain_d582b53b-1acc-41c2-b806-58883b0d6c10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_JointVentureFormationMember_3e86f147-cf5c-4ec4-9632-d1c7433ea7db" xlink:href="pagp-20231231.xsd#pagp_JointVentureFormationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_d582b53b-1acc-41c2-b806-58883b0d6c10" xlink:to="loc_pagp_JointVentureFormationMember_3e86f147-cf5c-4ec4-9632-d1c7433ea7db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInPartnersCapitalRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3bea35a2-635c-4902-a096-6da02b5b3ce2" xlink:to="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest_68b579c4-1cff-4734-972e-29cbd8cb23be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest_68b579c4-1cff-4734-972e-29cbd8cb23be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_93936ea6-33fb-4ff7-8dd7-7f4f21c23297" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_ProfitLoss_93936ea6-33fb-4ff7-8dd7-7f4f21c23297" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountDistributions_bc80f692-5959-47e4-82ae-5d33bcaf965a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_PartnersCapitalAccountDistributions_bc80f692-5959-47e4-82ae-5d33bcaf965a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalDeferredTaxAsset_129cbe15-9114-4f3f-b32f-be97b4bf38bb" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalDeferredTaxAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_pagp_PartnersCapitalDeferredTaxAsset_129cbe15-9114-4f3f-b32f-be97b4bf38bb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_15fb35de-2d94-445d-9c25-3e7ab597771b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_15fb35de-2d94-445d-9c25-3e7ab597771b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountUnitBasedCompensation_6849e798-64cc-452f-bea1-493783b41066" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountUnitBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_PartnersCapitalAccountUnitBasedCompensation_6849e798-64cc-452f-bea1-493783b41066" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary_6f339f53-854e-4834-8337-2028b9f41264" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestChangesRepurchaseOfSharesBySubsidiary_6f339f53-854e-4834-8337-2028b9f41264" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountContributions_1df5aae3-ea32-4898-9c5b-8a1e3ed99a18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountContributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_PartnersCapitalAccountContributions_1df5aae3-ea32-4898-9c5b-8a1e3ed99a18" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountAcquisitions_2fc4be84-ec89-469d-9487-4cae370d7f53" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_PartnersCapitalAccountAcquisitions_2fc4be84-ec89-469d-9487-4cae370d7f53" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalOther_5c2be2fd-e9ef-4de3-8ee1-55f9fa870ce3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_f1c6a371-8df6-47ba-8fae-d2c464d1b7ed" xlink:to="loc_us-gaap_PartnersCapitalOther_5c2be2fd-e9ef-4de3-8ee1-55f9fa870ce3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest_842a4732-5a2e-40b2-b242-8482dcdb4a4a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsTables" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsTables"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_b8cd3bee-638e-4f40-8bb0-b46d0749f9d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_34cd463a-7f3a-44eb-9a33-d7c8b48c1746" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b8cd3bee-638e-4f40-8bb0-b46d0749f9d9" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_34cd463a-7f3a-44eb-9a33-d7c8b48c1746" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_b8e18ded-4179-4da4-aa79-7ef19a3f4724" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_34cd463a-7f3a-44eb-9a33-d7c8b48c1746" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_b8e18ded-4179-4da4-aa79-7ef19a3f4724" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b8e18ded-4179-4da4-aa79-7ef19a3f4724_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_b8e18ded-4179-4da4-aa79-7ef19a3f4724" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b8e18ded-4179-4da4-aa79-7ef19a3f4724_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a10456cf-7869-48cb-bbec-260524424f88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_b8e18ded-4179-4da4-aa79-7ef19a3f4724" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a10456cf-7869-48cb-bbec-260524424f88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_9d5edc94-d0ee-4d97-9bf5-74421158399e" xlink:href="pagp-20231231.xsd#pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a10456cf-7869-48cb-bbec-260524424f88" xlink:to="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_9d5edc94-d0ee-4d97-9bf5-74421158399e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_652f8fd8-c862-4016-b3bd-4017d5363183" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a10456cf-7869-48cb-bbec-260524424f88" xlink:to="loc_pagp_CactusIIPipelineLLCMember_652f8fd8-c862-4016-b3bd-4017d5363183" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_b3670674-aeb4-497a-a03b-9121f7278bbf" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a10456cf-7869-48cb-bbec-260524424f88" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_b3670674-aeb4-497a-a03b-9121f7278bbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9bb68886-d2e3-48dd-8a3b-ccd43bc5aae5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_34cd463a-7f3a-44eb-9a33-d7c8b48c1746" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9bb68886-d2e3-48dd-8a3b-ccd43bc5aae5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9bb68886-d2e3-48dd-8a3b-ccd43bc5aae5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9bb68886-d2e3-48dd-8a3b-ccd43bc5aae5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9bb68886-d2e3-48dd-8a3b-ccd43bc5aae5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c653a0e6-795d-4873-bbbf-d557322ea3f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9bb68886-d2e3-48dd-8a3b-ccd43bc5aae5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c653a0e6-795d-4873-bbbf-d557322ea3f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_4e0d8c5e-167d-4128-8e98-8b53a0245e06" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c653a0e6-795d-4873-bbbf-d557322ea3f3" xlink:to="loc_us-gaap_CustomerRelationshipsMember_4e0d8c5e-167d-4128-8e98-8b53a0245e06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_2aaec6aa-ccc8-4e45-be6e-0a0d3884b655" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_34cd463a-7f3a-44eb-9a33-d7c8b48c1746" xlink:to="loc_srt_CounterpartyNameAxis_2aaec6aa-ccc8-4e45-be6e-0a0d3884b655" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_2aaec6aa-ccc8-4e45-be6e-0a0d3884b655_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_2aaec6aa-ccc8-4e45-be6e-0a0d3884b655" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_2aaec6aa-ccc8-4e45-be6e-0a0d3884b655_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_703993db-1610-437d-a012-6137058965af" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_2aaec6aa-ccc8-4e45-be6e-0a0d3884b655" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_703993db-1610-437d-a012-6137058965af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_38ed6332-ed5f-4942-bf1d-e5b021cddfc4" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_703993db-1610-437d-a012-6137058965af" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_38ed6332-ed5f-4942-bf1d-e5b021cddfc4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_d287f6d3-04e2-40b3-9f23-a008b223b26f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_34cd463a-7f3a-44eb-9a33-d7c8b48c1746" xlink:to="loc_us-gaap_TransactionTypeAxis_d287f6d3-04e2-40b3-9f23-a008b223b26f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_d287f6d3-04e2-40b3-9f23-a008b223b26f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_d287f6d3-04e2-40b3-9f23-a008b223b26f" xlink:to="loc_us-gaap_TransactionDomain_d287f6d3-04e2-40b3-9f23-a008b223b26f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_fc5b4db7-ca68-48e3-b310-cf6714421373" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_d287f6d3-04e2-40b3-9f23-a008b223b26f" xlink:to="loc_us-gaap_TransactionDomain_fc5b4db7-ca68-48e3-b310-cf6714421373" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_JointVentureFormationMember_dfeca993-af44-4675-a39d-bfcfa9e4e848" xlink:href="pagp-20231231.xsd#pagp_JointVentureFormationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_fc5b4db7-ca68-48e3-b310-cf6714421373" xlink:to="loc_pagp_JointVentureFormationMember_dfeca993-af44-4675-a39d-bfcfa9e4e848" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementMember_9d77363c-6775-422c-bf31-232037708bc2" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_fc5b4db7-ca68-48e3-b310-cf6714421373" xlink:to="loc_pagp_ModifiedSharingArrangementMember_9d77363c-6775-422c-bf31-232037708bc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_d1cb0ea2-0457-4a27-a89c-1c7eb95dec72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b8cd3bee-638e-4f40-8bb0-b46d0749f9d9" xlink:to="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_d1cb0ea2-0457-4a27-a89c-1c7eb95dec72" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock_5f60ea63-3c25-47ab-b8e7-6ca6039d1e8a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b8cd3bee-638e-4f40-8bb0-b46d0749f9d9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock_5f60ea63-3c25-47ab-b8e7-6ca6039d1e8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ScheduleOfPartnersCapitalTableTextBlock_e01ce17d-937c-4f34-a7e7-271f70d36ed7" xlink:href="pagp-20231231.xsd#pagp_ScheduleOfPartnersCapitalTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b8cd3bee-638e-4f40-8bb0-b46d0749f9d9" xlink:to="loc_pagp_ScheduleOfPartnersCapitalTableTextBlock_e01ce17d-937c-4f34-a7e7-271f70d36ed7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ScheduleOfModifiedRevenueSharingArrangementTableTextBlock_b972548b-70eb-4105-bff0-357fc5b744fc" xlink:href="pagp-20231231.xsd#pagp_ScheduleOfModifiedRevenueSharingArrangementTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b8cd3bee-638e-4f40-8bb0-b46d0749f9d9" xlink:to="loc_pagp_ScheduleOfModifiedRevenueSharingArrangementTableTextBlock_b972548b-70eb-4105-bff0-357fc5b744fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaInformationTextBlock_d4caec3c-418c-44dd-aa93-bb8dc717abcf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionProFormaInformationTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b8cd3bee-638e-4f40-8bb0-b46d0749f9d9" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaInformationTextBlock_d4caec3c-418c-44dd-aa93-bb8dc717abcf" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PartnersCapitalandDistributionsTables" xlink:type="simple" xlink:href="pagp-20231231.xsd#PartnersCapitalandDistributionsTables"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PartnersCapitalandDistributionsTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionLineItems_d6927c8b-c63b-499d-8f27-39c70649e528" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionsTable_41199735-e252-4b15-a0e2-3318eaf1446b" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_d6927c8b-c63b-499d-8f27-39c70649e528" xlink:to="loc_pagp_PartnersCapitalAndDistributionsTable_41199735-e252-4b15-a0e2-3318eaf1446b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_b422b80e-f233-404b-b831-f3c4506b5b18" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_41199735-e252-4b15-a0e2-3318eaf1446b" xlink:to="loc_dei_LegalEntityAxis_b422b80e-f233-404b-b831-f3c4506b5b18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_b422b80e-f233-404b-b831-f3c4506b5b18_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_b422b80e-f233-404b-b831-f3c4506b5b18" xlink:to="loc_dei_EntityDomain_b422b80e-f233-404b-b831-f3c4506b5b18_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_e6216bca-054a-43ac-805c-9f97865af697" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_b422b80e-f233-404b-b831-f3c4506b5b18" xlink:to="loc_dei_EntityDomain_e6216bca-054a-43ac-805c-9f97865af697" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_a8ec1aa0-c2dc-49d6-a57d-bea5e1329975" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_e6216bca-054a-43ac-805c-9f97865af697" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_a8ec1aa0-c2dc-49d6-a57d-bea5e1329975" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_bd4a0b74-4e9e-4bc8-9e26-2923b8e64ce0" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_e6216bca-054a-43ac-805c-9f97865af697" xlink:to="loc_pagp_PlainsAAPLPMember_bd4a0b74-4e9e-4bc8-9e26-2923b8e64ce0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_945c1611-b340-4b10-b271-25e6da795725" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_41199735-e252-4b15-a0e2-3318eaf1446b" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_945c1611-b340-4b10-b271-25e6da795725" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_945c1611-b340-4b10-b271-25e6da795725_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_945c1611-b340-4b10-b271-25e6da795725" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_945c1611-b340-4b10-b271-25e6da795725_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_e526ddbc-f8a8-4179-811f-84608939224e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_945c1611-b340-4b10-b271-25e6da795725" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_e526ddbc-f8a8-4179-811f-84608939224e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_a8735878-a337-446f-a182-a0837d1b0e68" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_e526ddbc-f8a8-4179-811f-84608939224e" xlink:to="loc_pagp_SharesClassAMember_a8735878-a337-446f-a182-a0837d1b0e68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeriesAPreferredUnitsMember_92fdfbc5-8bac-441e-9a4b-397619808ee4" xlink:href="pagp-20231231.xsd#pagp_SeriesAPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_e526ddbc-f8a8-4179-811f-84608939224e" xlink:to="loc_pagp_SeriesAPreferredUnitsMember_92fdfbc5-8bac-441e-9a4b-397619808ee4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeriesBPreferredUnitsMember_517160c8-2597-4fda-b620-1091d5128f42" xlink:href="pagp-20231231.xsd#pagp_SeriesBPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_e526ddbc-f8a8-4179-811f-84608939224e" xlink:to="loc_pagp_SeriesBPreferredUnitsMember_517160c8-2597-4fda-b620-1091d5128f42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CommonUnitsMember_1bd1f847-f50b-460d-afda-d2eddd430e37" xlink:href="pagp-20231231.xsd#pagp_CommonUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_e526ddbc-f8a8-4179-811f-84608939224e" xlink:to="loc_pagp_CommonUnitsMember_1bd1f847-f50b-460d-afda-d2eddd430e37" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockholdersEquityTableTextBlock_5ecb504f-e01b-45d0-96fb-0b028a4814f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockholdersEquityTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_d6927c8b-c63b-499d-8f27-39c70649e528" xlink:to="loc_us-gaap_ScheduleOfStockholdersEquityTableTextBlock_5ecb504f-e01b-45d0-96fb-0b028a4814f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionsMadeToLimitedPartnerByDistributionTableTextBlock_4119b24b-8761-4e8d-92d3-c1cfc8c9e9f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionsMadeToLimitedPartnerByDistributionTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_d6927c8b-c63b-499d-8f27-39c70649e528" xlink:to="loc_us-gaap_DistributionsMadeToLimitedPartnerByDistributionTableTextBlock_4119b24b-8761-4e8d-92d3-c1cfc8c9e9f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DistributionsMadeToNoncontrollingInterestsTableTextBlock_807ab965-8251-4411-90b4-62e82d5264e1" xlink:href="pagp-20231231.xsd#pagp_DistributionsMadeToNoncontrollingInterestsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_d6927c8b-c63b-499d-8f27-39c70649e528" xlink:to="loc_pagp_DistributionsMadeToNoncontrollingInterestsTableTextBlock_807ab965-8251-4411-90b4-62e82d5264e1" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesTables" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesTables"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_0ca95ab1-8da1-4015-bfc6-2ba075e84d1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_DerivativeTable_0ca95ab1-8da1-4015-bfc6-2ba075e84d1f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_1bc7088a-6241-467a-9731-2df0e8817673" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_0ca95ab1-8da1-4015-bfc6-2ba075e84d1f" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_1bc7088a-6241-467a-9731-2df0e8817673" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_1bc7088a-6241-467a-9731-2df0e8817673_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_1bc7088a-6241-467a-9731-2df0e8817673" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_1bc7088a-6241-467a-9731-2df0e8817673_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5a143d36-d798-42e9-94e4-93b6712caf63" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_1bc7088a-6241-467a-9731-2df0e8817673" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5a143d36-d798-42e9-94e4-93b6712caf63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_550c85e2-2488-45d2-a6c7-55c35089ccf3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_5a143d36-d798-42e9-94e4-93b6712caf63" xlink:to="loc_us-gaap_CommodityContractMember_550c85e2-2488-45d2-a6c7-55c35089ccf3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_98d59dd6-26f7-4d6f-9796-01690a16cf9c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_5a143d36-d798-42e9-94e4-93b6712caf63" xlink:to="loc_us-gaap_InterestRateSwapMember_98d59dd6-26f7-4d6f-9796-01690a16cf9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfNotionalAmountsOfOutstandingDerivativePositionsTableTextBlock_f1ad2cf1-9afc-42ff-8051-0a3c7434b334" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfNotionalAmountsOfOutstandingDerivativePositionsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_ScheduleOfNotionalAmountsOfOutstandingDerivativePositionsTableTextBlock_f1ad2cf1-9afc-42ff-8051-0a3c7434b334" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock_ac3041f6-ebe1-4358-810a-1f7b837e811c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock_ac3041f6-ebe1-4358-810a-1f7b837e811c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDueToFromBrokerDealersAndClearingOrganizationsTextBlock_271ca77b-4bd7-4c33-9d9a-5931b1b0fbe9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDueToFromBrokerDealersAndClearingOrganizationsTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_ScheduleOfDueToFromBrokerDealersAndClearingOrganizationsTextBlock_271ca77b-4bd7-4c33-9d9a-5931b1b0fbe9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock_3b2586c0-c45c-4d16-9ee3-41aac2b07ce7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock_3b2586c0-c45c-4d16-9ee3-41aac2b07ce7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDerivativeInstrumentsTextBlock_b811a55b-92e4-4e73-bcfa-120a065d89af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDerivativeInstrumentsTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_ScheduleOfDerivativeInstrumentsTextBlock_b811a55b-92e4-4e73-bcfa-120a065d89af" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashFlowHedgesIncludedInAccumulatedOtherComprehensiveIncomeLossTableTextBlock_84dc0273-4f23-42b8-9818-4aa50bfffb9e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfCashFlowHedgesIncludedInAccumulatedOtherComprehensiveIncomeLossTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_ScheduleOfCashFlowHedgesIncludedInAccumulatedOtherComprehensiveIncomeLossTableTextBlock_84dc0273-4f23-42b8-9818-4aa50bfffb9e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_998b5f0c-6be4-4b73-aac0-cf6a73722596" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_998b5f0c-6be4-4b73-aac0-cf6a73722596" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTableTextBlock_17e37cb4-5ca3-4658-b56c-5ca4cdb85459" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7daea0a2-1b12-4b93-a25a-c2ed73dd4c0b" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTableTextBlock_17e37cb4-5ca3-4658-b56c-5ca4cdb85459" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/OrganizationandBasisofConsolidationandPresentationDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#OrganizationandBasisofConsolidationandPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/OrganizationandBasisofConsolidationandPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OrganizationAndBasisOfPresentationLineItems_a88575e7-cbbc-4ead-92df-f01fe13d79ad" xlink:href="pagp-20231231.xsd#pagp_OrganizationAndBasisOfPresentationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_3e0957a8-ea77-4183-8afa-df58b93c8f5f" xlink:href="pagp-20231231.xsd#pagp_OrganizationConsolidationAndPresentationOfFinancialStatementsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_OrganizationAndBasisOfPresentationLineItems_a88575e7-cbbc-4ead-92df-f01fe13d79ad" xlink:to="loc_pagp_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_3e0957a8-ea77-4183-8afa-df58b93c8f5f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_6fd60af1-2993-4578-b994-135e8b70b1e5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_3e0957a8-ea77-4183-8afa-df58b93c8f5f" xlink:to="loc_srt_OwnershipAxis_6fd60af1-2993-4578-b994-135e8b70b1e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_6fd60af1-2993-4578-b994-135e8b70b1e5_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_6fd60af1-2993-4578-b994-135e8b70b1e5" xlink:to="loc_srt_OwnershipDomain_6fd60af1-2993-4578-b994-135e8b70b1e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_ccc6c97e-53da-4f97-af6f-befacf5115b7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_6fd60af1-2993-4578-b994-135e8b70b1e5" xlink:to="loc_srt_OwnershipDomain_ccc6c97e-53da-4f97-af6f-befacf5115b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanGPLLCMember_88d08603-c467-4f12-95c1-56568c05d3ba" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanGPLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_ccc6c97e-53da-4f97-af6f-befacf5115b7" xlink:to="loc_pagp_PlainsAllAmericanGPLLCMember_88d08603-c467-4f12-95c1-56568c05d3ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_24ed025d-007b-40be-bc08-3951ae45a311" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_ccc6c97e-53da-4f97-af6f-befacf5115b7" xlink:to="loc_pagp_PlainsAAPLPMember_24ed025d-007b-40be-bc08-3951ae45a311" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_0a16378e-72b2-4dbd-8bbc-cc1542cd3744" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_ccc6c97e-53da-4f97-af6f-befacf5115b7" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_0a16378e-72b2-4dbd-8bbc-cc1542cd3744" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_d3b19386-3925-416f-9042-22f192c4929e" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_3e0957a8-ea77-4183-8afa-df58b93c8f5f" xlink:to="loc_dei_LegalEntityAxis_d3b19386-3925-416f-9042-22f192c4929e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_d3b19386-3925-416f-9042-22f192c4929e_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_d3b19386-3925-416f-9042-22f192c4929e" xlink:to="loc_dei_EntityDomain_d3b19386-3925-416f-9042-22f192c4929e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_792c8cd0-66ae-4a8a-a112-c9ec45bbdc22" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_d3b19386-3925-416f-9042-22f192c4929e" xlink:to="loc_dei_EntityDomain_792c8cd0-66ae-4a8a-a112-c9ec45bbdc22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_09f86006-da9d-436d-9eea-a15f1d292231" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_792c8cd0-66ae-4a8a-a112-c9ec45bbdc22" xlink:to="loc_pagp_PlainsAAPLPMember_09f86006-da9d-436d-9eea-a15f1d292231" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_da1a94fa-cc2a-4234-9a4f-d6e1a8781034" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_OrganizationConsolidationAndPresentationOfFinancialStatementsTable_3e0957a8-ea77-4183-8afa-df58b93c8f5f" xlink:to="loc_srt_ConsolidatedEntitiesAxis_da1a94fa-cc2a-4234-9a4f-d6e1a8781034" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_da1a94fa-cc2a-4234-9a4f-d6e1a8781034_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_da1a94fa-cc2a-4234-9a4f-d6e1a8781034" xlink:to="loc_srt_ConsolidatedEntitiesDomain_da1a94fa-cc2a-4234-9a4f-d6e1a8781034_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_865b8514-fc72-481f-9450-177a5425a06a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_da1a94fa-cc2a-4234-9a4f-d6e1a8781034" xlink:to="loc_srt_ConsolidatedEntitiesDomain_865b8514-fc72-481f-9450-177a5425a06a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanGPLLCMember_605eebda-922a-4e0c-922c-60200065e9f1" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanGPLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_865b8514-fc72-481f-9450-177a5425a06a" xlink:to="loc_pagp_PlainsAllAmericanGPLLCMember_605eebda-922a-4e0c-922c-60200065e9f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntityExcludingVariableInterestEntitiesVIEMember_de13c192-23ca-4285-a635-17df01c29ab1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntityExcludingVariableInterestEntitiesVIEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_865b8514-fc72-481f-9450-177a5425a06a" xlink:to="loc_srt_ConsolidatedEntityExcludingVariableInterestEntitiesVIEMember_de13c192-23ca-4285-a635-17df01c29ab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_b53b682a-a221-4319-a3e2-8b4f0ecb84a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_OrganizationAndBasisOfPresentationLineItems_a88575e7-cbbc-4ead-92df-f01fe13d79ad" xlink:to="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_b53b682a-a221-4319-a3e2-8b4f0ecb84a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterestUnits_2f5e0129-5340-411a-92f8-b01bc8f164b3" xlink:href="pagp-20231231.xsd#pagp_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterestUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_OrganizationAndBasisOfPresentationLineItems_a88575e7-cbbc-4ead-92df-f01fe13d79ad" xlink:to="loc_pagp_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterestUnits_2f5e0129-5340-411a-92f8-b01bc8f164b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_25992476-2a2d-4702-a617-5e5bd21b884b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_OrganizationAndBasisOfPresentationLineItems_a88575e7-cbbc-4ead-92df-f01fe13d79ad" xlink:to="loc_us-gaap_NumberOfOperatingSegments_25992476-2a2d-4702-a617-5e5bd21b884b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_788b462c-1184-4149-b378-c61d9fc2726c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_OrganizationAndBasisOfPresentationLineItems_a88575e7-cbbc-4ead-92df-f01fe13d79ad" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_788b462c-1184-4149-b378-c61d9fc2726c" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/RevenuesandAccountsReceivableDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#RevenuesandAccountsReceivableDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/RevenuesandAccountsReceivableDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_b3172d7a-9665-4340-9985-bcf7e5245f48" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_dbd28d0f-6bd7-457e-b35f-0efeef9fb318" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_b3172d7a-9665-4340-9985-bcf7e5245f48" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_dbd28d0f-6bd7-457e-b35f-0efeef9fb318" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_9af591db-d51e-4b09-86b7-8f4f46132114" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_dbd28d0f-6bd7-457e-b35f-0efeef9fb318" xlink:to="loc_srt_ConsolidationItemsAxis_9af591db-d51e-4b09-86b7-8f4f46132114" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_9af591db-d51e-4b09-86b7-8f4f46132114_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_9af591db-d51e-4b09-86b7-8f4f46132114" xlink:to="loc_srt_ConsolidationItemsDomain_9af591db-d51e-4b09-86b7-8f4f46132114_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_1bb7e8d6-d61b-4c9e-bf72-04e6e9f1346f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_9af591db-d51e-4b09-86b7-8f4f46132114" xlink:to="loc_srt_ConsolidationItemsDomain_1bb7e8d6-d61b-4c9e-bf72-04e6e9f1346f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_cb0a11a4-b299-4884-aa17-e4e344cced94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_1bb7e8d6-d61b-4c9e-bf72-04e6e9f1346f" xlink:to="loc_us-gaap_OperatingSegmentsMember_cb0a11a4-b299-4884-aa17-e4e344cced94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_1a2bbbb4-bd1f-4cdc-a462-20142faf0d8b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_dbd28d0f-6bd7-457e-b35f-0efeef9fb318" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_1a2bbbb4-bd1f-4cdc-a462-20142faf0d8b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1a2bbbb4-bd1f-4cdc-a462-20142faf0d8b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1a2bbbb4-bd1f-4cdc-a462-20142faf0d8b" xlink:to="loc_us-gaap_SegmentDomain_1a2bbbb4-bd1f-4cdc-a462-20142faf0d8b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_ee18040c-02d5-4ba7-8a8a-c0a5371ab1ce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1a2bbbb4-bd1f-4cdc-a462-20142faf0d8b" xlink:to="loc_us-gaap_SegmentDomain_ee18040c-02d5-4ba7-8a8a-c0a5371ab1ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilSegmentMember_94739b3a-b998-4712-9337-ca1f3da94530" xlink:href="pagp-20231231.xsd#pagp_CrudeOilSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ee18040c-02d5-4ba7-8a8a-c0a5371ab1ce" xlink:to="loc_pagp_CrudeOilSegmentMember_94739b3a-b998-4712-9337-ca1f3da94530" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NaturalGasLiquidsSegmentMember_2336730e-337e-45ea-a195-ef402928b8ce" xlink:href="pagp-20231231.xsd#pagp_NaturalGasLiquidsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ee18040c-02d5-4ba7-8a8a-c0a5371ab1ce" xlink:to="loc_pagp_NaturalGasLiquidsSegmentMember_2336730e-337e-45ea-a195-ef402928b8ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_5f5d06b6-9aee-4b3f-aed5-28731899394f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_dbd28d0f-6bd7-457e-b35f-0efeef9fb318" xlink:to="loc_srt_ProductOrServiceAxis_5f5d06b6-9aee-4b3f-aed5-28731899394f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5f5d06b6-9aee-4b3f-aed5-28731899394f_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_5f5d06b6-9aee-4b3f-aed5-28731899394f" xlink:to="loc_srt_ProductsAndServicesDomain_5f5d06b6-9aee-4b3f-aed5-28731899394f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b937e355-b723-4138-9633-4a24ffd7e1ff" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_5f5d06b6-9aee-4b3f-aed5-28731899394f" xlink:to="loc_srt_ProductsAndServicesDomain_b937e355-b723-4138-9633-4a24ffd7e1ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_a8650b71-1720-47b6-b2fe-eb82843ab9c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b937e355-b723-4138-9633-4a24ffd7e1ff" xlink:to="loc_us-gaap_ProductMember_a8650b71-1720-47b6-b2fe-eb82843ab9c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_TransportationRevenueMember_e9996571-d144-4791-8696-16df4ac3c463" xlink:href="pagp-20231231.xsd#pagp_TransportationRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b937e355-b723-4138-9633-4a24ffd7e1ff" xlink:to="loc_pagp_TransportationRevenueMember_e9996571-d144-4791-8696-16df4ac3c463" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_TerminallingStorageAndOtherRevenueMember_9db7648a-2dc6-4123-8199-474e9eb52cbb" xlink:href="pagp-20231231.xsd#pagp_TerminallingStorageAndOtherRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b937e355-b723-4138-9633-4a24ffd7e1ff" xlink:to="loc_pagp_TerminallingStorageAndOtherRevenueMember_9db7648a-2dc6-4123-8199-474e9eb52cbb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d85258d4-b6a8-4d8b-b31f-536f5aa47a21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_b3172d7a-9665-4340-9985-bcf7e5245f48" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_d85258d4-b6a8-4d8b-b31f-536f5aa47a21" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/RevenuesandAccountsReceivableSegmentRevenueDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#RevenuesandAccountsReceivableSegmentRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/RevenuesandAccountsReceivableSegmentRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_d5d4693f-7339-47b2-bb64-155403df015c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_db7cab39-3d3f-4b06-ba47-a83a91647859" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_d5d4693f-7339-47b2-bb64-155403df015c" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_db7cab39-3d3f-4b06-ba47-a83a91647859" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_c4209d9e-6866-4c1e-8ff4-8e4181091852" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_db7cab39-3d3f-4b06-ba47-a83a91647859" xlink:to="loc_srt_ConsolidationItemsAxis_c4209d9e-6866-4c1e-8ff4-8e4181091852" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_c4209d9e-6866-4c1e-8ff4-8e4181091852_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_c4209d9e-6866-4c1e-8ff4-8e4181091852" xlink:to="loc_srt_ConsolidationItemsDomain_c4209d9e-6866-4c1e-8ff4-8e4181091852_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_33fc2878-151c-4b87-ab8f-6adb7f394005" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_c4209d9e-6866-4c1e-8ff4-8e4181091852" xlink:to="loc_srt_ConsolidationItemsDomain_33fc2878-151c-4b87-ab8f-6adb7f394005" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_8ae8b4f6-c97b-4380-b632-4d22720fb019" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_33fc2878-151c-4b87-ab8f-6adb7f394005" xlink:to="loc_us-gaap_OperatingSegmentsMember_8ae8b4f6-c97b-4380-b632-4d22720fb019" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_2ddce29c-c0dc-45bc-b671-7c7a1b1b7a2c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_33fc2878-151c-4b87-ab8f-6adb7f394005" xlink:to="loc_us-gaap_IntersegmentEliminationMember_2ddce29c-c0dc-45bc-b671-7c7a1b1b7a2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_29750164-9667-4c52-8ce6-eb655edbe351" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_db7cab39-3d3f-4b06-ba47-a83a91647859" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_29750164-9667-4c52-8ce6-eb655edbe351" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_29750164-9667-4c52-8ce6-eb655edbe351_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_29750164-9667-4c52-8ce6-eb655edbe351" xlink:to="loc_us-gaap_SegmentDomain_29750164-9667-4c52-8ce6-eb655edbe351_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_804690e3-3968-4a68-8123-7dfb343c71d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_29750164-9667-4c52-8ce6-eb655edbe351" xlink:to="loc_us-gaap_SegmentDomain_804690e3-3968-4a68-8123-7dfb343c71d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilSegmentMember_afa4eeb1-186d-4177-8a3c-6e14f0a0abff" xlink:href="pagp-20231231.xsd#pagp_CrudeOilSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_804690e3-3968-4a68-8123-7dfb343c71d6" xlink:to="loc_pagp_CrudeOilSegmentMember_afa4eeb1-186d-4177-8a3c-6e14f0a0abff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NaturalGasLiquidsSegmentMember_92d403d7-43d7-4224-8a36-3dcb6423f5a6" xlink:href="pagp-20231231.xsd#pagp_NaturalGasLiquidsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_804690e3-3968-4a68-8123-7dfb343c71d6" xlink:to="loc_pagp_NaturalGasLiquidsSegmentMember_92d403d7-43d7-4224-8a36-3dcb6423f5a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_686e3442-4731-4ca6-bd4d-ebd12c6b28b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_d5d4693f-7339-47b2-bb64-155403df015c" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_686e3442-4731-4ca6-bd4d-ebd12c6b28b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueNotFromContractWithCustomer_22db0514-881a-4472-b535-d3f6772818d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueNotFromContractWithCustomer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_d5d4693f-7339-47b2-bb64-155403df015c" xlink:to="loc_us-gaap_RevenueNotFromContractWithCustomer_22db0514-881a-4472-b535-d3f6772818d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_ea12df37-b4e2-4235-92d5-2db679fce2f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_d5d4693f-7339-47b2-bb64-155403df015c" xlink:to="loc_us-gaap_Revenues_ea12df37-b4e2-4235-92d5-2db679fce2f2" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/RevenuesandAccountsReceivableCounterpartyDeficienciesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#RevenuesandAccountsReceivableCounterpartyDeficienciesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/RevenuesandAccountsReceivableCounterpartyDeficienciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractWithCustomerAssetAndLiabilityLineItems_a83049c3-dced-4c21-a38c-9ea0f65e9c8d" xlink:href="pagp-20231231.xsd#pagp_ContractWithCustomerAssetAndLiabilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractWithCustomerAssetAndLiabilityTable_8d713369-db11-4760-85cb-ee58e1862d8b" xlink:href="pagp-20231231.xsd#pagp_ContractWithCustomerAssetAndLiabilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_ContractWithCustomerAssetAndLiabilityLineItems_a83049c3-dced-4c21-a38c-9ea0f65e9c8d" xlink:to="loc_pagp_ContractWithCustomerAssetAndLiabilityTable_8d713369-db11-4760-85cb-ee58e1862d8b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_de0c469b-4250-44a8-b6eb-d18615eb992e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ContractWithCustomerAssetAndLiabilityTable_8d713369-db11-4760-85cb-ee58e1862d8b" xlink:to="loc_us-gaap_TypeOfArrangementAxis_de0c469b-4250-44a8-b6eb-d18615eb992e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_de0c469b-4250-44a8-b6eb-d18615eb992e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_de0c469b-4250-44a8-b6eb-d18615eb992e" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_de0c469b-4250-44a8-b6eb-d18615eb992e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_871484d1-3bb9-42c1-aaa9-59f3c5329e81" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_de0c469b-4250-44a8-b6eb-d18615eb992e" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_871484d1-3bb9-42c1-aaa9-59f3c5329e81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_MinimumVolumeCommitmentAgreementsMember_db4d5d22-771d-480a-bba7-71ce0417aeba" xlink:href="pagp-20231231.xsd#pagp_MinimumVolumeCommitmentAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_871484d1-3bb9-42c1-aaa9-59f3c5329e81" xlink:to="loc_pagp_MinimumVolumeCommitmentAgreementsMember_db4d5d22-771d-480a-bba7-71ce0417aeba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_665b1d60-e80b-48a7-8d55-1ec9a0fd646d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ContractWithCustomerAssetAndLiabilityLineItems_a83049c3-dced-4c21-a38c-9ea0f65e9c8d" xlink:to="loc_us-gaap_ContractWithCustomerLiability_665b1d60-e80b-48a7-8d55-1ec9a0fd646d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/RevenuesandAccountsReceivableContractBalancesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#RevenuesandAccountsReceivableContractBalancesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/RevenuesandAccountsReceivableContractBalancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractWithCustomerAssetAndLiabilityLineItems_e3a04362-7f28-4a60-8463-5d758257d54f" xlink:href="pagp-20231231.xsd#pagp_ContractWithCustomerAssetAndLiabilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractWithCustomerAssetAndLiabilityTable_1a230915-ae4f-4e4b-a990-5451230be5ea" xlink:href="pagp-20231231.xsd#pagp_ContractWithCustomerAssetAndLiabilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_ContractWithCustomerAssetAndLiabilityLineItems_e3a04362-7f28-4a60-8463-5d758257d54f" xlink:to="loc_pagp_ContractWithCustomerAssetAndLiabilityTable_1a230915-ae4f-4e4b-a990-5451230be5ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_8b7653c2-0713-46d7-ad3f-ce2a96d6b603" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ContractWithCustomerAssetAndLiabilityTable_1a230915-ae4f-4e4b-a990-5451230be5ea" xlink:to="loc_us-gaap_TypeOfArrangementAxis_8b7653c2-0713-46d7-ad3f-ce2a96d6b603" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_8b7653c2-0713-46d7-ad3f-ce2a96d6b603_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_8b7653c2-0713-46d7-ad3f-ce2a96d6b603" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_8b7653c2-0713-46d7-ad3f-ce2a96d6b603_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_43ae1bba-e918-4778-90c1-fe26ff321619" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_8b7653c2-0713-46d7-ad3f-ce2a96d6b603" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_43ae1bba-e918-4778-90c1-fe26ff321619" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GasProcessingAgreementThatWasEnteredIntoInConjunctionWithThePurchaseOfAnAdditionalOwnershipInterestInCertainStraddlePlantsMember_9f07ed10-0eab-4bd4-a249-6ab2906353a2" xlink:href="pagp-20231231.xsd#pagp_GasProcessingAgreementThatWasEnteredIntoInConjunctionWithThePurchaseOfAnAdditionalOwnershipInterestInCertainStraddlePlantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_43ae1bba-e918-4778-90c1-fe26ff321619" xlink:to="loc_pagp_GasProcessingAgreementThatWasEnteredIntoInConjunctionWithThePurchaseOfAnAdditionalOwnershipInterestInCertainStraddlePlantsMember_9f07ed10-0eab-4bd4-a249-6ab2906353a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ChangeInContractWithCustomerLiabilityRollForward_a5f4f7cc-b9d3-4293-913e-572a39710eed" xlink:href="pagp-20231231.xsd#pagp_ChangeInContractWithCustomerLiabilityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ContractWithCustomerAssetAndLiabilityLineItems_e3a04362-7f28-4a60-8463-5d758257d54f" xlink:to="loc_pagp_ChangeInContractWithCustomerLiabilityRollForward_a5f4f7cc-b9d3-4293-913e-572a39710eed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_cf732508-9271-4640-93d0-7da3337f9be7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ChangeInContractWithCustomerLiabilityRollForward_a5f4f7cc-b9d3-4293-913e-572a39710eed" xlink:to="loc_us-gaap_ContractWithCustomerLiability_cf732508-9271-4640-93d0-7da3337f9be7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_8a85715b-48ec-47e0-917b-046d93843ef4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ChangeInContractWithCustomerLiabilityRollForward_a5f4f7cc-b9d3-4293-913e-572a39710eed" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_8a85715b-48ec-47e0-917b-046d93843ef4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractwithCustomerLiabilityAdditions_8c3ae2c8-52d5-40c0-b7af-020277753e95" xlink:href="pagp-20231231.xsd#pagp_ContractwithCustomerLiabilityAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ChangeInContractWithCustomerLiabilityRollForward_a5f4f7cc-b9d3-4293-913e-572a39710eed" xlink:to="loc_pagp_ContractwithCustomerLiabilityAdditions_8c3ae2c8-52d5-40c0-b7af-020277753e95" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractwithCustomerLiabilityOther_174bde6b-165c-4b90-adaf-dbc89ef7838f" xlink:href="pagp-20231231.xsd#pagp_ContractwithCustomerLiabilityOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ChangeInContractWithCustomerLiabilityRollForward_a5f4f7cc-b9d3-4293-913e-572a39710eed" xlink:to="loc_pagp_ContractwithCustomerLiabilityOther_174bde6b-165c-4b90-adaf-dbc89ef7838f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_d12af036-3c2a-4a80-a74d-5788ddf7b891" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractWithCustomerLiabilityRevenueRecognizedTerm_97849b4c-3089-43fa-b118-2477d25e8065" xlink:href="pagp-20231231.xsd#pagp_ContractWithCustomerLiabilityRevenueRecognizedTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ContractWithCustomerAssetAndLiabilityLineItems_e3a04362-7f28-4a60-8463-5d758257d54f" xlink:to="loc_pagp_ContractWithCustomerLiabilityRevenueRecognizedTerm_97849b4c-3089-43fa-b118-2477d25e8065" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/RevenuesandAccountsReceivablePerformanceObligationsDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#RevenuesandAccountsReceivablePerformanceObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/RevenuesandAccountsReceivablePerformanceObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0d040e74-e739-4b68-9aa3-ba27d6be2bba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2d5e1734-80d4-4aed-8ee2-90e1d37b5961" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0d040e74-e739-4b68-9aa3-ba27d6be2bba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2d5e1734-80d4-4aed-8ee2-90e1d37b5961" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_b67ab1ed-b3aa-416d-9660-90759f7aa814" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2d5e1734-80d4-4aed-8ee2-90e1d37b5961" xlink:to="loc_srt_ProductOrServiceAxis_b67ab1ed-b3aa-416d-9660-90759f7aa814" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b67ab1ed-b3aa-416d-9660-90759f7aa814_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_b67ab1ed-b3aa-416d-9660-90759f7aa814" xlink:to="loc_srt_ProductsAndServicesDomain_b67ab1ed-b3aa-416d-9660-90759f7aa814_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e6d7f1c4-61dc-47fc-9bf3-6f195cd42790" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_b67ab1ed-b3aa-416d-9660-90759f7aa814" xlink:to="loc_srt_ProductsAndServicesDomain_e6d7f1c4-61dc-47fc-9bf3-6f195cd42790" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PipelineRevenuesSupportedByMinimumVolumeCommitmentsAndLongTermCapacityAgreementsMember_7640bad6-9659-4e55-a7dd-7a93b977591d" xlink:href="pagp-20231231.xsd#pagp_PipelineRevenuesSupportedByMinimumVolumeCommitmentsAndLongTermCapacityAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e6d7f1c4-61dc-47fc-9bf3-6f195cd42790" xlink:to="loc_pagp_PipelineRevenuesSupportedByMinimumVolumeCommitmentsAndLongTermCapacityAgreementsMember_7640bad6-9659-4e55-a7dd-7a93b977591d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_TerminallingLongTermStorageAndThroughputAgreementsRevenuesMember_adfe7aeb-361b-4d52-b38b-17cbcf6cbfb3" xlink:href="pagp-20231231.xsd#pagp_TerminallingLongTermStorageAndThroughputAgreementsRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e6d7f1c4-61dc-47fc-9bf3-6f195cd42790" xlink:to="loc_pagp_TerminallingLongTermStorageAndThroughputAgreementsRevenuesMember_adfe7aeb-361b-4d52-b38b-17cbcf6cbfb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_717eb3e4-4dd3-48db-a006-e53b10910c35" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2d5e1734-80d4-4aed-8ee2-90e1d37b5961" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_717eb3e4-4dd3-48db-a006-e53b10910c35" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_5c689830-1d23-4518-b199-4a079f5a9c32" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0d040e74-e739-4b68-9aa3-ba27d6be2bba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_5c689830-1d23-4518-b199-4a079f5a9c32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_d529fd81-5b4a-4efc-8b0e-cdcd1d017f72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0d040e74-e739-4b68-9aa3-ba27d6be2bba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_d529fd81-5b4a-4efc-8b0e-cdcd1d017f72" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/RevenuesandAccountsReceivablePerformanceObligationsDetails_1" xlink:type="simple" xlink:href="pagp-20231231.xsd#RevenuesandAccountsReceivablePerformanceObligationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/RevenuesandAccountsReceivablePerformanceObligationsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0d040e74-e739-4b68-9aa3-ba27d6be2bba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2d5e1734-80d4-4aed-8ee2-90e1d37b5961" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0d040e74-e739-4b68-9aa3-ba27d6be2bba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2d5e1734-80d4-4aed-8ee2-90e1d37b5961" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_b67ab1ed-b3aa-416d-9660-90759f7aa814" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2d5e1734-80d4-4aed-8ee2-90e1d37b5961" xlink:to="loc_srt_ProductOrServiceAxis_b67ab1ed-b3aa-416d-9660-90759f7aa814" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b67ab1ed-b3aa-416d-9660-90759f7aa814_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_b67ab1ed-b3aa-416d-9660-90759f7aa814" xlink:to="loc_srt_ProductsAndServicesDomain_b67ab1ed-b3aa-416d-9660-90759f7aa814_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e6d7f1c4-61dc-47fc-9bf3-6f195cd42790" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_b67ab1ed-b3aa-416d-9660-90759f7aa814" xlink:to="loc_srt_ProductsAndServicesDomain_e6d7f1c4-61dc-47fc-9bf3-6f195cd42790" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PipelineRevenuesSupportedByMinimumVolumeCommitmentsAndLongTermCapacityAgreementsMember_7640bad6-9659-4e55-a7dd-7a93b977591d" xlink:href="pagp-20231231.xsd#pagp_PipelineRevenuesSupportedByMinimumVolumeCommitmentsAndLongTermCapacityAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e6d7f1c4-61dc-47fc-9bf3-6f195cd42790" xlink:to="loc_pagp_PipelineRevenuesSupportedByMinimumVolumeCommitmentsAndLongTermCapacityAgreementsMember_7640bad6-9659-4e55-a7dd-7a93b977591d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_TerminallingLongTermStorageAndThroughputAgreementsRevenuesMember_adfe7aeb-361b-4d52-b38b-17cbcf6cbfb3" xlink:href="pagp-20231231.xsd#pagp_TerminallingLongTermStorageAndThroughputAgreementsRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e6d7f1c4-61dc-47fc-9bf3-6f195cd42790" xlink:to="loc_pagp_TerminallingLongTermStorageAndThroughputAgreementsRevenuesMember_adfe7aeb-361b-4d52-b38b-17cbcf6cbfb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_5c689830-1d23-4518-b199-4a079f5a9c32" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0d040e74-e739-4b68-9aa3-ba27d6be2bba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_5c689830-1d23-4518-b199-4a079f5a9c32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_d529fd81-5b4a-4efc-8b0e-cdcd1d017f72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0d040e74-e739-4b68-9aa3-ba27d6be2bba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_d529fd81-5b4a-4efc-8b0e-cdcd1d017f72" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/NetIncomePerClassAShareDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#NetIncomePerClassAShareDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/NetIncomePerClassAShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BasicAndDilutedEarningsPerShareLineItems_6e069eb9-6d11-45e3-959c-d870e1335bf7" xlink:href="pagp-20231231.xsd#pagp_BasicAndDilutedEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ComputationOfBasicAndDilutedEarningsPerLimitedPartnerUnitTable_823f45a2-26c4-44d8-b6ae-2eae6d2dc76a" xlink:href="pagp-20231231.xsd#pagp_ComputationOfBasicAndDilutedEarningsPerLimitedPartnerUnitTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_BasicAndDilutedEarningsPerShareLineItems_6e069eb9-6d11-45e3-959c-d870e1335bf7" xlink:to="loc_pagp_ComputationOfBasicAndDilutedEarningsPerLimitedPartnerUnitTable_823f45a2-26c4-44d8-b6ae-2eae6d2dc76a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_3bc78607-1707-44c8-85e4-29e7c12862e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ComputationOfBasicAndDilutedEarningsPerLimitedPartnerUnitTable_823f45a2-26c4-44d8-b6ae-2eae6d2dc76a" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_3bc78607-1707-44c8-85e4-29e7c12862e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_3bc78607-1707-44c8-85e4-29e7c12862e7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_3bc78607-1707-44c8-85e4-29e7c12862e7" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_3bc78607-1707-44c8-85e4-29e7c12862e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_57c461e2-2b70-4afe-a569-4d2588d8e928" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_3bc78607-1707-44c8-85e4-29e7c12862e7" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_57c461e2-2b70-4afe-a569-4d2588d8e928" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AAPUnitsMember_7dee7d70-7430-4b10-9533-130a4b074fc7" xlink:href="pagp-20231231.xsd#pagp_AAPUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_57c461e2-2b70-4afe-a569-4d2588d8e928" xlink:to="loc_pagp_AAPUnitsMember_7dee7d70-7430-4b10-9533-130a4b074fc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_2be43391-c861-472d-8c10-eab130c43f54" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_57c461e2-2b70-4afe-a569-4d2588d8e928" xlink:to="loc_pagp_SharesClassAMember_2be43391-c861-472d-8c10-eab130c43f54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6e3d40b9-50e4-4bc2-a44a-fbcfec0a3afd" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ComputationOfBasicAndDilutedEarningsPerLimitedPartnerUnitTable_823f45a2-26c4-44d8-b6ae-2eae6d2dc76a" xlink:to="loc_srt_RangeAxis_6e3d40b9-50e4-4bc2-a44a-fbcfec0a3afd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6e3d40b9-50e4-4bc2-a44a-fbcfec0a3afd_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6e3d40b9-50e4-4bc2-a44a-fbcfec0a3afd" xlink:to="loc_srt_RangeMember_6e3d40b9-50e4-4bc2-a44a-fbcfec0a3afd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_32a9f6fc-13e1-4b8b-a3ac-b2ad8d4b5b74" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6e3d40b9-50e4-4bc2-a44a-fbcfec0a3afd" xlink:to="loc_srt_RangeMember_32a9f6fc-13e1-4b8b-a3ac-b2ad8d4b5b74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_1e3a94d1-db1d-48c3-a005-b6465908145b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_32a9f6fc-13e1-4b8b-a3ac-b2ad8d4b5b74" xlink:to="loc_srt_WeightedAverageMember_1e3a94d1-db1d-48c3-a005-b6465908145b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_278fdd6d-9890-48b0-8e03-9dbae8d2f73c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_BasicAndDilutedEarningsPerShareLineItems_6e069eb9-6d11-45e3-959c-d870e1335bf7" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_278fdd6d-9890-48b0-8e03-9dbae8d2f73c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_4bc1a6ba-da94-4be9-bf44-44ae801737f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_BasicAndDilutedEarningsPerShareLineItems_6e069eb9-6d11-45e3-959c-d870e1335bf7" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_4bc1a6ba-da94-4be9-bf44-44ae801737f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_78ccb5fe-8348-4e2a-9b31-14c11d48ff9c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_4bc1a6ba-da94-4be9-bf44-44ae801737f9" xlink:to="loc_us-gaap_NetIncomeLoss_78ccb5fe-8348-4e2a-9b31-14c11d48ff9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_bcd1835b-efc9-4245-86ed-2043d62ec5a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_4bc1a6ba-da94-4be9-bf44-44ae801737f9" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_bcd1835b-efc9-4245-86ed-2043d62ec5a0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_a26df999-138e-4f3f-8226-fae6749c9275" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_4bc1a6ba-da94-4be9-bf44-44ae801737f9" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_a26df999-138e-4f3f-8226-fae6749c9275" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_870f8f2d-de04-4ef1-8e3e-4160e2c1eaa4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_4bc1a6ba-da94-4be9-bf44-44ae801737f9" xlink:to="loc_us-gaap_EarningsPerShareBasic_870f8f2d-de04-4ef1-8e3e-4160e2c1eaa4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_d07a2976-5d86-4ab8-8854-6d54a804f6bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_4bc1a6ba-da94-4be9-bf44-44ae801737f9" xlink:to="loc_us-gaap_EarningsPerShareDiluted_d07a2976-5d86-4ab8-8854-6d54a804f6bb" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/InventoryLinefillandLongtermInventoryComponentsofInventoryLinefillandLongtermInventoryDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#InventoryLinefillandLongtermInventoryComponentsofInventoryLinefillandLongtermInventoryDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/InventoryLinefillandLongtermInventoryComponentsofInventoryLinefillandLongtermInventoryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryCurrentTable_3d075282-be29-4233-9225-96aac7606f1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryCurrentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_us-gaap_InventoryCurrentTable_3d075282-be29-4233-9225-96aac7606f1a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryAxis_da28e6aa-21ab-422a-a8fe-7497137af314" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PublicUtilitiesInventoryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_InventoryCurrentTable_3d075282-be29-4233-9225-96aac7606f1a" xlink:to="loc_us-gaap_PublicUtilitiesInventoryAxis_da28e6aa-21ab-422a-a8fe-7497137af314" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_da28e6aa-21ab-422a-a8fe-7497137af314_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_da28e6aa-21ab-422a-a8fe-7497137af314" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_da28e6aa-21ab-422a-a8fe-7497137af314_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_70878822-2f86-43c1-8738-c93725677c18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_da28e6aa-21ab-422a-a8fe-7497137af314" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_70878822-2f86-43c1-8738-c93725677c18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CrudeOilMember_4682d9b5-e482-4779-bde1-44393ea0a489" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CrudeOilMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_70878822-2f86-43c1-8738-c93725677c18" xlink:to="loc_srt_CrudeOilMember_4682d9b5-e482-4779-bde1-44393ea0a489" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasLiquidsReservesMember_2eea9baa-ea25-49e0-8ac4-e89d820865a8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NaturalGasLiquidsReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_70878822-2f86-43c1-8738-c93725677c18" xlink:to="loc_srt_NaturalGasLiquidsReservesMember_2eea9baa-ea25-49e0-8ac4-e89d820865a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OtherInventoryMember_eab1245e-5d19-41c1-aa83-f52cc271f634" xlink:href="pagp-20231231.xsd#pagp_OtherInventoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_70878822-2f86-43c1-8738-c93725677c18" xlink:to="loc_pagp_OtherInventoryMember_eab1245e-5d19-41c1-aa83-f52cc271f634" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InventoryVolumesCurrent_4f3a94be-145e-4907-a4de-3938758f25ec" xlink:href="pagp-20231231.xsd#pagp_InventoryVolumesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_pagp_InventoryVolumesCurrent_4f3a94be-145e-4907-a4de-3938758f25ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InventoryVolumesLinefill_e5156f0f-9e3b-4491-80ba-d2e1afe890c0" xlink:href="pagp-20231231.xsd#pagp_InventoryVolumesLinefill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_pagp_InventoryVolumesLinefill_e5156f0f-9e3b-4491-80ba-d2e1afe890c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InventoryVolumesNoncurrent_2e74a90d-5a56-4c06-bfa9-d1feaf2a1466" xlink:href="pagp-20231231.xsd#pagp_InventoryVolumesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_pagp_InventoryVolumesNoncurrent_2e74a90d-5a56-4c06-bfa9-d1feaf2a1466" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_93e0da4f-8359-4309-9018-8d39b7f274f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_us-gaap_InventoryNet_93e0da4f-8359-4309-9018-8d39b7f274f2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_Linefill_cbacdb05-763c-4617-96fe-63fadc32d819" xlink:href="pagp-20231231.xsd#pagp_Linefill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_pagp_Linefill_cbacdb05-763c-4617-96fe-63fadc32d819" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNoncurrent_2ab66bb0-fd55-4473-ae94-93ce4ff0d670" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_us-gaap_InventoryNoncurrent_2ab66bb0-fd55-4473-ae94-93ce4ff0d670" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InventoryCurrentAndNoncurrent_149daeb3-2034-47b1-a4aa-48f09a68f2fe" xlink:href="pagp-20231231.xsd#pagp_InventoryCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_pagp_InventoryCurrentAndNoncurrent_149daeb3-2034-47b1-a4aa-48f09a68f2fe" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InventoryWeightedAveragePricePerUnitCurrent_cbb3db18-cdbf-4ea0-b0e6-cb99312c94af" xlink:href="pagp-20231231.xsd#pagp_InventoryWeightedAveragePricePerUnitCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_pagp_InventoryWeightedAveragePricePerUnitCurrent_cbb3db18-cdbf-4ea0-b0e6-cb99312c94af" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InventoryWeightedAveragePricePerUnitLinefill_965662ae-74c4-4597-89f4-96aa30d49702" xlink:href="pagp-20231231.xsd#pagp_InventoryWeightedAveragePricePerUnitLinefill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_pagp_InventoryWeightedAveragePricePerUnitLinefill_965662ae-74c4-4597-89f4-96aa30d49702" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InventoryWeightedAveragePricePerUnitNoncurrent_789b6e64-a584-4a5c-90d6-59acea30fab6" xlink:href="pagp-20231231.xsd#pagp_InventoryWeightedAveragePricePerUnitNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_681eaaf4-d7dc-496c-be13-5decfdafa75e" xlink:to="loc_pagp_InventoryWeightedAveragePricePerUnitNoncurrent_789b6e64-a584-4a5c-90d6-59acea30fab6" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PropertyandEquipmentComponentsofPropertyandEquipmentNetDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#PropertyandEquipmentComponentsofPropertyandEquipmentNetDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PropertyandEquipmentComponentsofPropertyandEquipmentNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_a9e32986-2477-49f2-9dc6-6d65fa771c4c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8d0534ae-3c57-4d6f-b3cb-288cb0df7d84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_a9e32986-2477-49f2-9dc6-6d65fa771c4c" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8d0534ae-3c57-4d6f-b3cb-288cb0df7d84" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2b932c40-c3cd-4ff7-a947-c487a4727cf3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8d0534ae-3c57-4d6f-b3cb-288cb0df7d84" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2b932c40-c3cd-4ff7-a947-c487a4727cf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2b932c40-c3cd-4ff7-a947-c487a4727cf3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2b932c40-c3cd-4ff7-a947-c487a4727cf3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2b932c40-c3cd-4ff7-a947-c487a4727cf3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b6dc4958-09e6-44b5-a8ee-500cead17a79" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2b932c40-c3cd-4ff7-a947-c487a4727cf3" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b6dc4958-09e6-44b5-a8ee-500cead17a79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PipelinesMember_1a8ea1fa-ffc5-4a9f-ae58-8870bf391523" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PipelinesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b6dc4958-09e6-44b5-a8ee-500cead17a79" xlink:to="loc_us-gaap_PipelinesMember_1a8ea1fa-ffc5-4a9f-ae58-8870bf391523" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilStorageTerminalAndTerminalFacilitiesMember_b38bad3e-08c0-4384-9ea0-9cdf3606ad9e" xlink:href="pagp-20231231.xsd#pagp_CrudeOilStorageTerminalAndTerminalFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b6dc4958-09e6-44b5-a8ee-500cead17a79" xlink:to="loc_pagp_CrudeOilStorageTerminalAndTerminalFacilitiesMember_b38bad3e-08c0-4384-9ea0-9cdf3606ad9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NGLStorageTerminalFractionationAndProcessingFacilitiesMember_bf62850e-1507-4d0f-bb4e-6da1295bf646" xlink:href="pagp-20231231.xsd#pagp_NGLStorageTerminalFractionationAndProcessingFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b6dc4958-09e6-44b5-a8ee-500cead17a79" xlink:to="loc_pagp_NGLStorageTerminalFractionationAndProcessingFacilitiesMember_bf62850e-1507-4d0f-bb4e-6da1295bf646" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OfficePropertyAndEquipmentAndRollingStockMember_93ebb431-2e3c-40e2-8ecb-913361457e0b" xlink:href="pagp-20231231.xsd#pagp_OfficePropertyAndEquipmentAndRollingStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b6dc4958-09e6-44b5-a8ee-500cead17a79" xlink:to="loc_pagp_OfficePropertyAndEquipmentAndRollingStockMember_93ebb431-2e3c-40e2-8ecb-913361457e0b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_730a03bc-54fd-4bdb-b383-81be221c6972" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b6dc4958-09e6-44b5-a8ee-500cead17a79" xlink:to="loc_us-gaap_ConstructionInProgressMember_730a03bc-54fd-4bdb-b383-81be221c6972" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LandAndOtherMember_987cc719-5fbe-485f-b83a-29479ad7d9bc" xlink:href="pagp-20231231.xsd#pagp_LandAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b6dc4958-09e6-44b5-a8ee-500cead17a79" xlink:to="loc_pagp_LandAndOtherMember_987cc719-5fbe-485f-b83a-29479ad7d9bc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_b89a2fc0-1342-4a55-814f-9988252fc1f9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8d0534ae-3c57-4d6f-b3cb-288cb0df7d84" xlink:to="loc_srt_RangeAxis_b89a2fc0-1342-4a55-814f-9988252fc1f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b89a2fc0-1342-4a55-814f-9988252fc1f9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_b89a2fc0-1342-4a55-814f-9988252fc1f9" xlink:to="loc_srt_RangeMember_b89a2fc0-1342-4a55-814f-9988252fc1f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_60566eae-f3ff-41b3-8d42-9c0908ce945b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_b89a2fc0-1342-4a55-814f-9988252fc1f9" xlink:to="loc_srt_RangeMember_60566eae-f3ff-41b3-8d42-9c0908ce945b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_1833180b-3099-4dd0-bf89-b7a1d7be5cf2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_60566eae-f3ff-41b3-8d42-9c0908ce945b" xlink:to="loc_srt_MinimumMember_1833180b-3099-4dd0-bf89-b7a1d7be5cf2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_d7e3e2b8-7980-43e5-8ad7-100d2a41b018" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_60566eae-f3ff-41b3-8d42-9c0908ce945b" xlink:to="loc_srt_MaximumMember_d7e3e2b8-7980-43e5-8ad7-100d2a41b018" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_1537d731-9c8e-4fbe-80cc-f4de6b1ea9ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8d0534ae-3c57-4d6f-b3cb-288cb0df7d84" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_1537d731-9c8e-4fbe-80cc-f4de6b1ea9ac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1537d731-9c8e-4fbe-80cc-f4de6b1ea9ac_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1537d731-9c8e-4fbe-80cc-f4de6b1ea9ac" xlink:to="loc_us-gaap_SegmentDomain_1537d731-9c8e-4fbe-80cc-f4de6b1ea9ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_5e6e9203-3678-44b5-a382-41b8bb1956d3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1537d731-9c8e-4fbe-80cc-f4de6b1ea9ac" xlink:to="loc_us-gaap_SegmentDomain_5e6e9203-3678-44b5-a382-41b8bb1956d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilSegmentMember_95f0823c-f83e-467d-bd5c-ca06dbb899a4" xlink:href="pagp-20231231.xsd#pagp_CrudeOilSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5e6e9203-3678-44b5-a382-41b8bb1956d3" xlink:to="loc_pagp_CrudeOilSegmentMember_95f0823c-f83e-467d-bd5c-ca06dbb899a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NaturalGasLiquidsSegmentMember_4e6ce7d6-08cb-4075-96d3-7755c8799b3e" xlink:href="pagp-20231231.xsd#pagp_NaturalGasLiquidsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5e6e9203-3678-44b5-a382-41b8bb1956d3" xlink:to="loc_pagp_NaturalGasLiquidsSegmentMember_4e6ce7d6-08cb-4075-96d3-7755c8799b3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_440033d0-7cfd-471f-b2a4-e0a5bef6c5a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_a9e32986-2477-49f2-9dc6-6d65fa771c4c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_440033d0-7cfd-471f-b2a4-e0a5bef6c5a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_2b1c87ed-ac62-4d28-9824-0e3a7bb8f817" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_a9e32986-2477-49f2-9dc6-6d65fa771c4c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_2b1c87ed-ac62-4d28-9824-0e3a7bb8f817" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_43d64b30-0470-4e9f-a461-daf9558719bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_a9e32986-2477-49f2-9dc6-6d65fa771c4c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_43d64b30-0470-4e9f-a461-daf9558719bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_703fd23b-0815-4157-9bfc-61fded9d2506" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_a9e32986-2477-49f2-9dc6-6d65fa771c4c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_703fd23b-0815-4157-9bfc-61fded9d2506" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PropertyandEquipmentNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#PropertyandEquipmentNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PropertyandEquipmentNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_caa063d0-3044-4ca0-898c-7125df2bddee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_be2164cb-a820-4c9b-96eb-1f2850b108b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_caa063d0-3044-4ca0-898c-7125df2bddee" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_be2164cb-a820-4c9b-96eb-1f2850b108b6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_322aff2c-c864-4487-85fe-43d0e60ec167" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_be2164cb-a820-4c9b-96eb-1f2850b108b6" xlink:to="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_322aff2c-c864-4487-85fe-43d0e60ec167" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_322aff2c-c864-4487-85fe-43d0e60ec167_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_322aff2c-c864-4487-85fe-43d0e60ec167" xlink:to="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_322aff2c-c864-4487-85fe-43d0e60ec167_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_0ee214ff-aa6a-4696-9d7e-e9444ec02add" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_322aff2c-c864-4487-85fe-43d0e60ec167" xlink:to="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_0ee214ff-aa6a-4696-9d7e-e9444ec02add" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CaliforniaAssetsMember_efc36837-2e5f-4c28-a551-75d1d99aaad3" xlink:href="pagp-20231231.xsd#pagp_CaliforniaAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_0ee214ff-aa6a-4696-9d7e-e9444ec02add" xlink:to="loc_pagp_CaliforniaAssetsMember_efc36837-2e5f-4c28-a551-75d1d99aaad3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilStorageTerminalAssetsMember_c918ddea-fc68-4b0d-8d1d-f0f85b8111bf" xlink:href="pagp-20231231.xsd#pagp_CrudeOilStorageTerminalAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_0ee214ff-aa6a-4696-9d7e-e9444ec02add" xlink:to="loc_pagp_CrudeOilStorageTerminalAssetsMember_c918ddea-fc68-4b0d-8d1d-f0f85b8111bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_18fd2599-d2df-45ab-ab91-7c76cdd13304" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_be2164cb-a820-4c9b-96eb-1f2850b108b6" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_18fd2599-d2df-45ab-ab91-7c76cdd13304" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_18fd2599-d2df-45ab-ab91-7c76cdd13304_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_18fd2599-d2df-45ab-ab91-7c76cdd13304" xlink:to="loc_us-gaap_SegmentDomain_18fd2599-d2df-45ab-ab91-7c76cdd13304_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9fa14cd0-4687-4415-8447-161e0518318c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_18fd2599-d2df-45ab-ab91-7c76cdd13304" xlink:to="loc_us-gaap_SegmentDomain_9fa14cd0-4687-4415-8447-161e0518318c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilSegmentMember_1892eb5d-f8c3-4095-bcd3-feb917bf7c2b" xlink:href="pagp-20231231.xsd#pagp_CrudeOilSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9fa14cd0-4687-4415-8447-161e0518318c" xlink:to="loc_pagp_CrudeOilSegmentMember_1892eb5d-f8c3-4095-bcd3-feb917bf7c2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d6d35e80-967f-4d47-88e4-d68cf1933b88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_be2164cb-a820-4c9b-96eb-1f2850b108b6" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d6d35e80-967f-4d47-88e4-d68cf1933b88" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d6d35e80-967f-4d47-88e4-d68cf1933b88_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d6d35e80-967f-4d47-88e4-d68cf1933b88" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d6d35e80-967f-4d47-88e4-d68cf1933b88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2b76cdc6-eba4-4db6-84f0-cff3703ff694" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d6d35e80-967f-4d47-88e4-d68cf1933b88" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2b76cdc6-eba4-4db6-84f0-cff3703ff694" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_583f5e3c-1860-4cd6-bd86-f4f18b9527f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2b76cdc6-eba4-4db6-84f0-cff3703ff694" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_583f5e3c-1860-4cd6-bd86-f4f18b9527f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_c8c76bc8-1bbb-4b48-9325-87e12ef8c39e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_be2164cb-a820-4c9b-96eb-1f2850b108b6" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_c8c76bc8-1bbb-4b48-9325-87e12ef8c39e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_c8c76bc8-1bbb-4b48-9325-87e12ef8c39e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_c8c76bc8-1bbb-4b48-9325-87e12ef8c39e" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_c8c76bc8-1bbb-4b48-9325-87e12ef8c39e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_776e1ff3-328d-41ba-a64c-013244740982" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_c8c76bc8-1bbb-4b48-9325-87e12ef8c39e" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_776e1ff3-328d-41ba-a64c-013244740982" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_6aec7bb5-0d58-495b-bf9c-f9e8cd3a2ae5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_776e1ff3-328d-41ba-a64c-013244740982" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_6aec7bb5-0d58-495b-bf9c-f9e8cd3a2ae5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_2ddd7b47-e77e-4712-a5c3-981b2e238799" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_be2164cb-a820-4c9b-96eb-1f2850b108b6" xlink:to="loc_us-gaap_ValuationTechniqueAxis_2ddd7b47-e77e-4712-a5c3-981b2e238799" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_2ddd7b47-e77e-4712-a5c3-981b2e238799_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_2ddd7b47-e77e-4712-a5c3-981b2e238799" xlink:to="loc_us-gaap_ValuationTechniqueDomain_2ddd7b47-e77e-4712-a5c3-981b2e238799_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_527b6719-6050-44af-ba3b-b1c3749d85a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_2ddd7b47-e77e-4712-a5c3-981b2e238799" xlink:to="loc_us-gaap_ValuationTechniqueDomain_527b6719-6050-44af-ba3b-b1c3749d85a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_3cec46e8-ca00-4ff3-bc6e-fd2d736082c5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_527b6719-6050-44af-ba3b-b1c3749d85a0" xlink:to="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_3cec46e8-ca00-4ff3-bc6e-fd2d736082c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_4c0c6fd2-058c-45a3-9f6d-348cdd638664" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_caa063d0-3044-4ca0-898c-7125df2bddee" xlink:to="loc_us-gaap_Depreciation_4c0c6fd2-058c-45a3-9f6d-348cdd638664" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressExpendituresIncurredButNotYetPaid_731e4c34-5b0b-4f61-b208-c9db8a186ad4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionInProgressExpendituresIncurredButNotYetPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_caa063d0-3044-4ca0-898c-7125df2bddee" xlink:to="loc_us-gaap_ConstructionInProgressExpendituresIncurredButNotYetPaid_731e4c34-5b0b-4f61-b208-c9db8a186ad4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_53bbee7c-b6c3-4dfd-87f3-89bcb024b8db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_caa063d0-3044-4ca0-898c-7125df2bddee" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_53bbee7c-b6c3-4dfd-87f3-89bcb024b8db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_3f596fa9-9f22-41bd-bac6-f1f2c1697034" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_53bbee7c-b6c3-4dfd-87f3-89bcb024b8db" xlink:to="loc_us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_3f596fa9-9f22-41bd-bac6-f1f2c1697034" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ImpairmentAnalysisCostOfCapitalTheoreticalMarketParticipant_2a5e4bfe-1c18-49ee-94ab-2b1bd5d56414" xlink:href="pagp-20231231.xsd#pagp_ImpairmentAnalysisCostOfCapitalTheoreticalMarketParticipant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_caa063d0-3044-4ca0-898c-7125df2bddee" xlink:to="loc_pagp_ImpairmentAnalysisCostOfCapitalTheoreticalMarketParticipant_2a5e4bfe-1c18-49ee-94ab-2b1bd5d56414" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsRattlerPermianTransactionNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsRattlerPermianTransactionNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsRattlerPermianTransactionNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_9690f238-b95a-4441-b5cb-127d90d616be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_9690f238-b95a-4441-b5cb-127d90d616be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9690f238-b95a-4441-b5cb-127d90d616be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_9690f238-b95a-4441-b5cb-127d90d616be" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9690f238-b95a-4441-b5cb-127d90d616be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_48546024-5c30-42b8-8afc-21ef7df1c495" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_9690f238-b95a-4441-b5cb-127d90d616be" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_48546024-5c30-42b8-8afc-21ef7df1c495" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_a45e3543-8228-4470-b8a3-6944b3fc6f3e" xlink:href="pagp-20231231.xsd#pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_48546024-5c30-42b8-8afc-21ef7df1c495" xlink:to="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_a45e3543-8228-4470-b8a3-6944b3fc6f3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OMOGJVLLCMember_e5c259e3-c2f7-454a-bec0-3c1da80d88e2" xlink:href="pagp-20231231.xsd#pagp_OMOGJVLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_a45e3543-8228-4470-b8a3-6944b3fc6f3e" xlink:to="loc_pagp_OMOGJVLLCMember_e5c259e3-c2f7-454a-bec0-3c1da80d88e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_cbd9d0aa-a3c3-4f2c-bb34-7b9ce1909d96" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_srt_OwnershipAxis_cbd9d0aa-a3c3-4f2c-bb34-7b9ce1909d96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_cbd9d0aa-a3c3-4f2c-bb34-7b9ce1909d96_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_cbd9d0aa-a3c3-4f2c-bb34-7b9ce1909d96" xlink:to="loc_srt_OwnershipDomain_cbd9d0aa-a3c3-4f2c-bb34-7b9ce1909d96_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_f350daa8-95f8-48d1-868f-54aa7053f37b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_cbd9d0aa-a3c3-4f2c-bb34-7b9ce1909d96" xlink:to="loc_srt_OwnershipDomain_f350daa8-95f8-48d1-868f-54aa7053f37b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_e6808f1c-4130-4804-91b5-d2af6db59394" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_f350daa8-95f8-48d1-868f-54aa7053f37b" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_e6808f1c-4130-4804-91b5-d2af6db59394" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_19f76d23-9831-4947-aa05-a0e4e80593e6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_19f76d23-9831-4947-aa05-a0e4e80593e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_19f76d23-9831-4947-aa05-a0e4e80593e6_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_19f76d23-9831-4947-aa05-a0e4e80593e6" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_19f76d23-9831-4947-aa05-a0e4e80593e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_6d7c4a57-1823-4aaa-ab82-edf8ad390c73" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_19f76d23-9831-4947-aa05-a0e4e80593e6" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_6d7c4a57-1823-4aaa-ab82-edf8ad390c73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OMOGJVLLCMember_e22aaef6-3cd5-4e7c-8a30-5c7de38081a3" xlink:href="pagp-20231231.xsd#pagp_OMOGJVLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_6d7c4a57-1823-4aaa-ab82-edf8ad390c73" xlink:to="loc_pagp_OMOGJVLLCMember_e22aaef6-3cd5-4e7c-8a30-5c7de38081a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_68c97a8b-34a3-42e9-8c58-041b9a2780bb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_srt_CounterpartyNameAxis_68c97a8b-34a3-42e9-8c58-041b9a2780bb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_68c97a8b-34a3-42e9-8c58-041b9a2780bb_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_68c97a8b-34a3-42e9-8c58-041b9a2780bb" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_68c97a8b-34a3-42e9-8c58-041b9a2780bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_813667ce-dd07-44b0-b0a1-df9ea45043e0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_68c97a8b-34a3-42e9-8c58-041b9a2780bb" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_813667ce-dd07-44b0-b0a1-df9ea45043e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_RattlerMidstreamOperatingLLCMember_a1a49069-898e-42a4-8627-f852d8b19a95" xlink:href="pagp-20231231.xsd#pagp_RattlerMidstreamOperatingLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_813667ce-dd07-44b0-b0a1-df9ea45043e0" xlink:to="loc_pagp_RattlerMidstreamOperatingLLCMember_a1a49069-898e-42a4-8627-f852d8b19a95" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9940f31c-ea2b-4e51-a4ed-943186d0488d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9940f31c-ea2b-4e51-a4ed-943186d0488d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9940f31c-ea2b-4e51-a4ed-943186d0488d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9940f31c-ea2b-4e51-a4ed-943186d0488d" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9940f31c-ea2b-4e51-a4ed-943186d0488d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5c514b23-8405-4625-a7bb-c3a0db30350b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9940f31c-ea2b-4e51-a4ed-943186d0488d" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5c514b23-8405-4625-a7bb-c3a0db30350b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_5c6a71f4-4aeb-4b90-8cf0-feb9e0e315be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5c514b23-8405-4625-a7bb-c3a0db30350b" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_5c6a71f4-4aeb-4b90-8cf0-feb9e0e315be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_6e663734-d3f6-4ee8-889f-c9347c7afa63" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_6e663734-d3f6-4ee8-889f-c9347c7afa63" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_6e663734-d3f6-4ee8-889f-c9347c7afa63_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_6e663734-d3f6-4ee8-889f-c9347c7afa63" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_6e663734-d3f6-4ee8-889f-c9347c7afa63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_d2854321-1b36-46fc-8550-c4058784f2aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_6e663734-d3f6-4ee8-889f-c9347c7afa63" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_d2854321-1b36-46fc-8550-c4058784f2aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_6883aa84-d036-4a1e-b467-4133c6852de1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_d2854321-1b36-46fc-8550-c4058784f2aa" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_6883aa84-d036-4a1e-b467-4133c6852de1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_e1956a67-19d9-49c9-b295-282675153660" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_us-gaap_ValuationTechniqueAxis_e1956a67-19d9-49c9-b295-282675153660" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_e1956a67-19d9-49c9-b295-282675153660_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_e1956a67-19d9-49c9-b295-282675153660" xlink:to="loc_us-gaap_ValuationTechniqueDomain_e1956a67-19d9-49c9-b295-282675153660_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_a6c509ec-bdf3-4679-9dd0-d5d49f11fa39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_e1956a67-19d9-49c9-b295-282675153660" xlink:to="loc_us-gaap_ValuationTechniqueDomain_a6c509ec-bdf3-4679-9dd0-d5d49f11fa39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_42fd4893-84fe-4f4e-9b8b-c21d1c4b37f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_a6c509ec-bdf3-4679-9dd0-d5d49f11fa39" xlink:to="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_42fd4893-84fe-4f4e-9b8b-c21d1c4b37f6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_a1b23808-e4fe-40b6-9a59-03bffa0a8cf9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_a1b23808-e4fe-40b6-9a59-03bffa0a8cf9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_a1b23808-e4fe-40b6-9a59-03bffa0a8cf9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_a1b23808-e4fe-40b6-9a59-03bffa0a8cf9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_a1b23808-e4fe-40b6-9a59-03bffa0a8cf9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_d025663c-05da-4587-af9d-86c9f60473a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_a1b23808-e4fe-40b6-9a59-03bffa0a8cf9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_d025663c-05da-4587-af9d-86c9f60473a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainslossesOnInvestmentsInUnconsolidatedEntitiesNetMember_c58c3e42-1bc5-4837-8388-217494338519" xlink:href="pagp-20231231.xsd#pagp_GainslossesOnInvestmentsInUnconsolidatedEntitiesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_d025663c-05da-4587-af9d-86c9f60473a0" xlink:to="loc_pagp_GainslossesOnInvestmentsInUnconsolidatedEntitiesNetMember_c58c3e42-1bc5-4837-8388-217494338519" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_40990fba-cf70-4785-83d4-88645646d0a0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_srt_RangeAxis_40990fba-cf70-4785-83d4-88645646d0a0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_40990fba-cf70-4785-83d4-88645646d0a0_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_40990fba-cf70-4785-83d4-88645646d0a0" xlink:to="loc_srt_RangeMember_40990fba-cf70-4785-83d4-88645646d0a0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_461bbb41-640b-4570-8e2c-c4ec3440aac3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_40990fba-cf70-4785-83d4-88645646d0a0" xlink:to="loc_srt_RangeMember_461bbb41-640b-4570-8e2c-c4ec3440aac3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5ddd9c58-08b7-494b-93ba-23e72383befa" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_461bbb41-640b-4570-8e2c-c4ec3440aac3" xlink:to="loc_srt_MinimumMember_5ddd9c58-08b7-494b-93ba-23e72383befa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_eda5f815-328e-4cb7-8314-d7a2748249e8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_461bbb41-640b-4570-8e2c-c4ec3440aac3" xlink:to="loc_srt_MaximumMember_eda5f815-328e-4cb7-8314-d7a2748249e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_99cf0c6b-8583-42c7-a29d-3e10751c1312" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_dei_LegalEntityAxis_99cf0c6b-8583-42c7-a29d-3e10751c1312" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_99cf0c6b-8583-42c7-a29d-3e10751c1312_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_99cf0c6b-8583-42c7-a29d-3e10751c1312" xlink:to="loc_dei_EntityDomain_99cf0c6b-8583-42c7-a29d-3e10751c1312_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_73a52e49-e42b-4b2f-bc1b-e573c32401df" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_99cf0c6b-8583-42c7-a29d-3e10751c1312" xlink:to="loc_dei_EntityDomain_73a52e49-e42b-4b2f-bc1b-e573c32401df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_95e77bcb-3bb6-4388-8377-1abdc181667a" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_73a52e49-e42b-4b2f-bc1b-e573c32401df" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_95e77bcb-3bb6-4388-8377-1abdc181667a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_26e88c88-c8d3-4644-af00-dc0bb23b2ba0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_26e88c88-c8d3-4644-af00-dc0bb23b2ba0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_26e88c88-c8d3-4644-af00-dc0bb23b2ba0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_26e88c88-c8d3-4644-af00-dc0bb23b2ba0" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_26e88c88-c8d3-4644-af00-dc0bb23b2ba0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_357434fc-3630-48b6-ad17-7ea9ffa6b71f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_26e88c88-c8d3-4644-af00-dc0bb23b2ba0" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_357434fc-3630-48b6-ad17-7ea9ffa6b71f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMember_2b6b162b-8809-482b-9f2c-f2637ca48259" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_357434fc-3630-48b6-ad17-7ea9ffa6b71f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMember_2b6b162b-8809-482b-9f2c-f2637ca48259" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_36c7b16b-de77-4819-8946-e7a971a997c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9a70da88-4464-4e54-9ce2-4ec8ff3b755d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_36c7b16b-de77-4819-8946-e7a971a997c0" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_36c7b16b-de77-4819-8946-e7a971a997c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_36c7b16b-de77-4819-8946-e7a971a997c0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_36c7b16b-de77-4819-8946-e7a971a997c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e9f0f6c4-9b31-4584-80af-5485ffee5517" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_36c7b16b-de77-4819-8946-e7a971a997c0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e9f0f6c4-9b31-4584-80af-5485ffee5517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_3c8ae461-63df-415f-9315-b98ebbeab98c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e9f0f6c4-9b31-4584-80af-5485ffee5517" xlink:to="loc_us-gaap_CustomerRelationshipsMember_3c8ae461-63df-415f-9315-b98ebbeab98c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_e693ee8c-5ce8-41fa-9db4-72a418339d71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_e693ee8c-5ce8-41fa-9db4-72a418339d71" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_5de16a31-ed39-42de-a0cf-776265bf0aa7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_5de16a31-ed39-42de-a0cf-776265bf0aa7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BusinessCombinationConsiderationTransferredNetToOwnershipInterest_15d4475f-7c50-4e9b-942b-ffd4b53c6cbe" xlink:href="pagp-20231231.xsd#pagp_BusinessCombinationConsiderationTransferredNetToOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_pagp_BusinessCombinationConsiderationTransferredNetToOwnershipInterest_15d4475f-7c50-4e9b-942b-ffd4b53c6cbe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_c5c6d72a-cafe-4f4b-97b9-d509bbf82ad3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_c5c6d72a-cafe-4f4b-97b9-d509bbf82ad3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage_448170c8-4929-4816-baa4-b155dc33737c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage_448170c8-4929-4816-baa4-b155dc33737c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_19804f34-aaae-4559-933c-b0f0301a076a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_19804f34-aaae-4559-933c-b0f0301a076a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireePercentage_d7330516-6c59-407e-bbd3-f667536f66c8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireePercentage_d7330516-6c59-407e-bbd3-f667536f66c8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1_95c2dbfa-35ad-4c4e-8d80-6ba53bb8cd4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1_95c2dbfa-35ad-4c4e-8d80-6ba53bb8cd4e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BusinessCombinationMeasurementInput_5ea3c431-14d3-42d6-a82b-efb8f51f0bde" xlink:href="pagp-20231231.xsd#pagp_BusinessCombinationMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_pagp_BusinessCombinationMeasurementInput_5ea3c431-14d3-42d6-a82b-efb8f51f0bde" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain_2ae7376b-4126-488f-b28b-27d63d991d36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain_2ae7376b-4126-488f-b28b-27d63d991d36" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_ba830ef0-738c-4210-aee6-90f1c2ddbb52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_ba830ef0-738c-4210-aee6-90f1c2ddbb52" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredIncludingEquityInterestInAcquireeHeldPriorToCombination1_96034ddd-2a02-4875-b5ff-c2416250a0c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferredIncludingEquityInterestInAcquireeHeldPriorToCombination1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_06a85594-2182-47f9-bb6c-450fa2f0f636" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredIncludingEquityInterestInAcquireeHeldPriorToCombination1_96034ddd-2a02-4875-b5ff-c2416250a0c3" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsScheduleofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsScheduleofAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsScheduleofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e3bbdd5a-ec5a-47ef-be8e-6cf05fbba8d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e3bbdd5a-ec5a-47ef-be8e-6cf05fbba8d4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_d43fa952-2b09-4855-bdff-bb1a46a553cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e3bbdd5a-ec5a-47ef-be8e-6cf05fbba8d4" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_d43fa952-2b09-4855-bdff-bb1a46a553cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d43fa952-2b09-4855-bdff-bb1a46a553cc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d43fa952-2b09-4855-bdff-bb1a46a553cc" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d43fa952-2b09-4855-bdff-bb1a46a553cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0c2eaeea-199f-482a-b4a6-fc3e99e2f872" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d43fa952-2b09-4855-bdff-bb1a46a553cc" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0c2eaeea-199f-482a-b4a6-fc3e99e2f872" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_5270c1f9-ac17-46ff-917e-3fe1b97468b3" xlink:href="pagp-20231231.xsd#pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0c2eaeea-199f-482a-b4a6-fc3e99e2f872" xlink:to="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_5270c1f9-ac17-46ff-917e-3fe1b97468b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_9e7bad7d-cdf9-4513-8655-37803a1674a3" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0c2eaeea-199f-482a-b4a6-fc3e99e2f872" xlink:to="loc_pagp_CactusIIPipelineLLCMember_9e7bad7d-cdf9-4513-8655-37803a1674a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_3122210f-3f2c-495e-a8c5-5e64228a19cb" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0c2eaeea-199f-482a-b4a6-fc3e99e2f872" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_3122210f-3f2c-495e-a8c5-5e64228a19cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_b8901b8a-ca41-4fad-a980-509396676e85" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e3bbdd5a-ec5a-47ef-be8e-6cf05fbba8d4" xlink:to="loc_srt_CounterpartyNameAxis_b8901b8a-ca41-4fad-a980-509396676e85" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_b8901b8a-ca41-4fad-a980-509396676e85_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_b8901b8a-ca41-4fad-a980-509396676e85" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_b8901b8a-ca41-4fad-a980-509396676e85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_69efc0a8-90a6-4159-b46f-b4574acfa83a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_b8901b8a-ca41-4fad-a980-509396676e85" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_69efc0a8-90a6-4159-b46f-b4574acfa83a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_65a34826-c2ea-467f-8cba-ea1f369430b4" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_69efc0a8-90a6-4159-b46f-b4574acfa83a" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_65a34826-c2ea-467f-8cba-ea1f369430b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_d36c9aea-7074-4ea6-b285-d37a8d7140be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e3bbdd5a-ec5a-47ef-be8e-6cf05fbba8d4" xlink:to="loc_us-gaap_TransactionTypeAxis_d36c9aea-7074-4ea6-b285-d37a8d7140be" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_d36c9aea-7074-4ea6-b285-d37a8d7140be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_d36c9aea-7074-4ea6-b285-d37a8d7140be" xlink:to="loc_us-gaap_TransactionDomain_d36c9aea-7074-4ea6-b285-d37a8d7140be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_935656b7-c4d0-454c-8a2c-88f73e202f92" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_d36c9aea-7074-4ea6-b285-d37a8d7140be" xlink:to="loc_us-gaap_TransactionDomain_935656b7-c4d0-454c-8a2c-88f73e202f92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_JointVentureFormationMember_8af2d044-c9e4-4641-8995-b853b119065e" xlink:href="pagp-20231231.xsd#pagp_JointVentureFormationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_935656b7-c4d0-454c-8a2c-88f73e202f92" xlink:to="loc_pagp_JointVentureFormationMember_8af2d044-c9e4-4641-8995-b853b119065e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_c25779ce-a27f-453f-9d93-1c655d4b2bb3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e3bbdd5a-ec5a-47ef-be8e-6cf05fbba8d4" xlink:to="loc_srt_RangeAxis_c25779ce-a27f-453f-9d93-1c655d4b2bb3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c25779ce-a27f-453f-9d93-1c655d4b2bb3_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_c25779ce-a27f-453f-9d93-1c655d4b2bb3" xlink:to="loc_srt_RangeMember_c25779ce-a27f-453f-9d93-1c655d4b2bb3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_eb12cc60-710c-4d5e-9f61-e8fe1814108d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_c25779ce-a27f-453f-9d93-1c655d4b2bb3" xlink:to="loc_srt_RangeMember_eb12cc60-710c-4d5e-9f61-e8fe1814108d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_35b04cc3-5c63-4929-abc3-4033f4918382" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_eb12cc60-710c-4d5e-9f61-e8fe1814108d" xlink:to="loc_srt_MinimumMember_35b04cc3-5c63-4929-abc3-4033f4918382" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_700b3220-24a9-4542-96f9-b86bd0458431" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_eb12cc60-710c-4d5e-9f61-e8fe1814108d" xlink:to="loc_srt_MaximumMember_700b3220-24a9-4542-96f9-b86bd0458431" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_e09b7855-3d6f-40ed-b90f-339c34ba4f11" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_e09b7855-3d6f-40ed-b90f-339c34ba4f11" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_164c20a4-57df-497a-9c57-192cadfa712b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_164c20a4-57df-497a-9c57-192cadfa712b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_c88ed3b8-8332-442f-affa-67d57dd4216a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_c88ed3b8-8332-442f-affa-67d57dd4216a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_b106cf3b-f05d-450d-b85e-2c69af740215" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_b106cf3b-f05d-450d-b85e-2c69af740215" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInvestmentInUnconsolidatedEntities_fcd7fa9b-eb50-4b72-ba08-5654179aa3e5" xlink:href="pagp-20231231.xsd#pagp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInvestmentInUnconsolidatedEntities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:to="loc_pagp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInvestmentInUnconsolidatedEntities_fcd7fa9b-eb50-4b72-ba08-5654179aa3e5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedWorkingCapitalAndOtherAssetsAndLiabilities_9194a395-d201-48ac-90d8-8f2e28817c5d" xlink:href="pagp-20231231.xsd#pagp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedWorkingCapitalAndOtherAssetsAndLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:to="loc_pagp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedWorkingCapitalAndOtherAssetsAndLiabilities_9194a395-d201-48ac-90d8-8f2e28817c5d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_1ba6b718-66bb-4ec7-9296-894253e55e33" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_af12898e-8eb8-48dc-8fae-8c60d804b0fe" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_1ba6b718-66bb-4ec7-9296-894253e55e33" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsScheduleofAmortizationExpenseDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsScheduleofAmortizationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsScheduleofAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_95d4357a-ce54-4f72-adfd-de5f48baec71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_95d4357a-ce54-4f72-adfd-de5f48baec71" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_c192b6e9-ab14-4eed-b662-67e6042461bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_95d4357a-ce54-4f72-adfd-de5f48baec71" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_c192b6e9-ab14-4eed-b662-67e6042461bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c192b6e9-ab14-4eed-b662-67e6042461bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_c192b6e9-ab14-4eed-b662-67e6042461bb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c192b6e9-ab14-4eed-b662-67e6042461bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bfad95c-11f1-49d5-9129-c7427a26b70c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_c192b6e9-ab14-4eed-b662-67e6042461bb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bfad95c-11f1-49d5-9129-c7427a26b70c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_054c4d6f-9fc2-4c60-9010-a074928c9fdc" xlink:href="pagp-20231231.xsd#pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bfad95c-11f1-49d5-9129-c7427a26b70c" xlink:to="loc_pagp_OMOGJVLLCAndSouthernDelawareGatheringAssetsMember_054c4d6f-9fc2-4c60-9010-a074928c9fdc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_0a029cc8-fd10-4446-b07c-9961f3991050" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bfad95c-11f1-49d5-9129-c7427a26b70c" xlink:to="loc_pagp_CactusIIPipelineLLCMember_0a029cc8-fd10-4446-b07c-9961f3991050" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_54ebef62-7ca7-47bc-a7e0-4afb83c907d3" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bfad95c-11f1-49d5-9129-c7427a26b70c" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_54ebef62-7ca7-47bc-a7e0-4afb83c907d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bca1f8e4-ba34-4645-88b9-ac1ac2a9c371" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_95d4357a-ce54-4f72-adfd-de5f48baec71" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bca1f8e4-ba34-4645-88b9-ac1ac2a9c371" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_bca1f8e4-ba34-4645-88b9-ac1ac2a9c371_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bca1f8e4-ba34-4645-88b9-ac1ac2a9c371" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_bca1f8e4-ba34-4645-88b9-ac1ac2a9c371_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ef869c63-5ebe-4877-a2bc-ac597f9339d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bca1f8e4-ba34-4645-88b9-ac1ac2a9c371" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ef869c63-5ebe-4877-a2bc-ac597f9339d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_826aca03-3d67-4a28-9c65-43cce9d1e085" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ef869c63-5ebe-4877-a2bc-ac597f9339d8" xlink:to="loc_us-gaap_CustomerRelationshipsMember_826aca03-3d67-4a28-9c65-43cce9d1e085" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_756b5885-f375-4398-8730-351df529b096" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_95d4357a-ce54-4f72-adfd-de5f48baec71" xlink:to="loc_us-gaap_TransactionTypeAxis_756b5885-f375-4398-8730-351df529b096" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_756b5885-f375-4398-8730-351df529b096_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_756b5885-f375-4398-8730-351df529b096" xlink:to="loc_us-gaap_TransactionDomain_756b5885-f375-4398-8730-351df529b096_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_f400fc9b-c4cb-4222-8d4e-fa7e897ae4ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_756b5885-f375-4398-8730-351df529b096" xlink:to="loc_us-gaap_TransactionDomain_f400fc9b-c4cb-4222-8d4e-fa7e897ae4ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_JointVentureFormationMember_35be6403-fbaa-4230-9914-e889afec8714" xlink:href="pagp-20231231.xsd#pagp_JointVentureFormationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_f400fc9b-c4cb-4222-8d4e-fa7e897ae4ac" xlink:to="loc_pagp_JointVentureFormationMember_35be6403-fbaa-4230-9914-e889afec8714" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_c98a8b63-e65e-48a2-8755-7fd3ca657ca1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_c98a8b63-e65e-48a2-8755-7fd3ca657ca1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentForAmortization_c58acef8-3d1d-48b0-8192-7836aec53be1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentForAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:to="loc_us-gaap_AdjustmentForAmortization_c58acef8-3d1d-48b0-8192-7836aec53be1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_9646bce9-af63-4f7a-ba29-d48770bba3d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_9646bce9-af63-4f7a-ba29-d48770bba3d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_4fc2edfc-319c-443c-9c6a-07c224f6c650" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_4fc2edfc-319c-443c-9c6a-07c224f6c650" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_a673baac-19b9-404f-b47d-c2fb5de68fcb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_a673baac-19b9-404f-b47d-c2fb5de68fcb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_ae4b9aac-ca0d-4120-85f0-5269e9f36ffe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_ae4b9aac-ca0d-4120-85f0-5269e9f36ffe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_50f45eda-1402-4272-aa66-71a56be0426d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_656593bd-20bc-4a49-a738-12351a3c81d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_50f45eda-1402-4272-aa66-71a56be0426d" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsCactusIINarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsCactusIINarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsCactusIINarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_2d214708-3646-4154-b792-170a90fc8dce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_2d214708-3646-4154-b792-170a90fc8dce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2d214708-3646-4154-b792-170a90fc8dce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2d214708-3646-4154-b792-170a90fc8dce" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2d214708-3646-4154-b792-170a90fc8dce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3cd45651-3666-4368-9302-a332d4bea434" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2d214708-3646-4154-b792-170a90fc8dce" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3cd45651-3666-4368-9302-a332d4bea434" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_904921ad-53a2-457e-b0c4-4b9a0f810b84" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3cd45651-3666-4368-9302-a332d4bea434" xlink:to="loc_pagp_CactusIIPipelineLLCMember_904921ad-53a2-457e-b0c4-4b9a0f810b84" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_92793edf-f38b-4d71-9325-6f14dcb4e242" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_srt_OwnershipAxis_92793edf-f38b-4d71-9325-6f14dcb4e242" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_92793edf-f38b-4d71-9325-6f14dcb4e242_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_92793edf-f38b-4d71-9325-6f14dcb4e242" xlink:to="loc_srt_OwnershipDomain_92793edf-f38b-4d71-9325-6f14dcb4e242_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_c45b3b81-f7a2-4d98-8ad0-02a271e74adb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_92793edf-f38b-4d71-9325-6f14dcb4e242" xlink:to="loc_srt_OwnershipDomain_c45b3b81-f7a2-4d98-8ad0-02a271e74adb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_f1082ff1-c0f2-4146-838f-dbb1d46509ee" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_c45b3b81-f7a2-4d98-8ad0-02a271e74adb" xlink:to="loc_pagp_CactusIIPipelineLLCMember_f1082ff1-c0f2-4146-838f-dbb1d46509ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aa323489-411f-4162-939a-b30d03110bb7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aa323489-411f-4162-939a-b30d03110bb7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_aa323489-411f-4162-939a-b30d03110bb7_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aa323489-411f-4162-939a-b30d03110bb7" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_aa323489-411f-4162-939a-b30d03110bb7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_7a6c2ea2-0053-4e51-abaf-54c579e28bd6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aa323489-411f-4162-939a-b30d03110bb7" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_7a6c2ea2-0053-4e51-abaf-54c579e28bd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_450c3d01-b5ee-460c-bdaa-a7faed01dff2" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_7a6c2ea2-0053-4e51-abaf-54c579e28bd6" xlink:to="loc_pagp_CactusIIPipelineLLCMember_450c3d01-b5ee-460c-bdaa-a7faed01dff2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_238a9eb7-6898-468a-8bf1-1954918d4ced" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_dei_LegalEntityAxis_238a9eb7-6898-468a-8bf1-1954918d4ced" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_238a9eb7-6898-468a-8bf1-1954918d4ced_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_238a9eb7-6898-468a-8bf1-1954918d4ced" xlink:to="loc_dei_EntityDomain_238a9eb7-6898-468a-8bf1-1954918d4ced_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_388af8c2-44e5-4826-aaf9-828ef9bd6bf4" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_238a9eb7-6898-468a-8bf1-1954918d4ced" xlink:to="loc_dei_EntityDomain_388af8c2-44e5-4826-aaf9-828ef9bd6bf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAndEnbridgeMember_c941e820-c6ff-408b-83ac-038965f62b87" xlink:href="pagp-20231231.xsd#pagp_PlainsAndEnbridgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_388af8c2-44e5-4826-aaf9-828ef9bd6bf4" xlink:to="loc_pagp_PlainsAndEnbridgeMember_c941e820-c6ff-408b-83ac-038965f62b87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EnbridgeMember_5e674239-9e43-41ed-ad8b-a179462ee6ba" xlink:href="pagp-20231231.xsd#pagp_EnbridgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_388af8c2-44e5-4826-aaf9-828ef9bd6bf4" xlink:to="loc_pagp_EnbridgeMember_5e674239-9e43-41ed-ad8b-a179462ee6ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_256b0d79-b7a5-4715-9578-9c70649e7618" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_srt_CounterpartyNameAxis_256b0d79-b7a5-4715-9578-9c70649e7618" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_256b0d79-b7a5-4715-9578-9c70649e7618_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_256b0d79-b7a5-4715-9578-9c70649e7618" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_256b0d79-b7a5-4715-9578-9c70649e7618_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6d51df49-ec0a-4f0a-8968-09b376b96758" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_256b0d79-b7a5-4715-9578-9c70649e7618" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6d51df49-ec0a-4f0a-8968-09b376b96758" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_WesternMidstreamPartnersLPMember_b67e020d-8f3d-4e61-982a-8eab603a4a13" xlink:href="pagp-20231231.xsd#pagp_WesternMidstreamPartnersLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6d51df49-ec0a-4f0a-8968-09b376b96758" xlink:to="loc_pagp_WesternMidstreamPartnersLPMember_b67e020d-8f3d-4e61-982a-8eab603a4a13" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_51037d6f-8764-48a4-9b6a-2288711071cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_51037d6f-8764-48a4-9b6a-2288711071cd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_51037d6f-8764-48a4-9b6a-2288711071cd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_51037d6f-8764-48a4-9b6a-2288711071cd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_51037d6f-8764-48a4-9b6a-2288711071cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d0f78cc2-4602-4b1c-ba0e-177d1f6c7ca2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_51037d6f-8764-48a4-9b6a-2288711071cd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d0f78cc2-4602-4b1c-ba0e-177d1f6c7ca2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_5de69b8f-2793-4939-baa0-9528cc004db7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d0f78cc2-4602-4b1c-ba0e-177d1f6c7ca2" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_5de69b8f-2793-4939-baa0-9528cc004db7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_733b8c7e-a3c3-41d1-bc15-a0021d9ee1b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_733b8c7e-a3c3-41d1-bc15-a0021d9ee1b6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_733b8c7e-a3c3-41d1-bc15-a0021d9ee1b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_733b8c7e-a3c3-41d1-bc15-a0021d9ee1b6" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_733b8c7e-a3c3-41d1-bc15-a0021d9ee1b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_8d3c73e2-ba67-4482-be76-79f2de741c15" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_733b8c7e-a3c3-41d1-bc15-a0021d9ee1b6" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_8d3c73e2-ba67-4482-be76-79f2de741c15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_befcd1cd-3353-4aa4-ad64-0f7a3f5b2b0a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_8d3c73e2-ba67-4482-be76-79f2de741c15" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_befcd1cd-3353-4aa4-ad64-0f7a3f5b2b0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_4868cc27-9fb6-47b1-88a0-c358ba399cfe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_us-gaap_ValuationTechniqueAxis_4868cc27-9fb6-47b1-88a0-c358ba399cfe" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_4868cc27-9fb6-47b1-88a0-c358ba399cfe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_4868cc27-9fb6-47b1-88a0-c358ba399cfe" xlink:to="loc_us-gaap_ValuationTechniqueDomain_4868cc27-9fb6-47b1-88a0-c358ba399cfe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_df9180e6-da81-4f19-831e-a855bc5c28ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_4868cc27-9fb6-47b1-88a0-c358ba399cfe" xlink:to="loc_us-gaap_ValuationTechniqueDomain_df9180e6-da81-4f19-831e-a855bc5c28ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_70ddb3e1-bc38-412f-9ae0-e542d548edc1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_df9180e6-da81-4f19-831e-a855bc5c28ac" xlink:to="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_70ddb3e1-bc38-412f-9ae0-e542d548edc1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_863bb1ae-8a7a-4719-a82c-41b72878ec73" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_863bb1ae-8a7a-4719-a82c-41b72878ec73" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_863bb1ae-8a7a-4719-a82c-41b72878ec73_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_863bb1ae-8a7a-4719-a82c-41b72878ec73" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_863bb1ae-8a7a-4719-a82c-41b72878ec73_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_7afb10a6-6662-4e42-addb-b720af92d5da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_863bb1ae-8a7a-4719-a82c-41b72878ec73" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_7afb10a6-6662-4e42-addb-b720af92d5da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMember_cfb1e4e3-2edd-455f-be46-6760e67bd83d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_7afb10a6-6662-4e42-addb-b720af92d5da" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMember_cfb1e4e3-2edd-455f-be46-6760e67bd83d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsAxis_b9a213cb-3f88-42dc-ba30-a0f82f999039" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_us-gaap_PartnerCapitalComponentsAxis_b9a213cb-3f88-42dc-ba30-a0f82f999039" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_b9a213cb-3f88-42dc-ba30-a0f82f999039_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_b9a213cb-3f88-42dc-ba30-a0f82f999039" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_b9a213cb-3f88-42dc-ba30-a0f82f999039_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_3a2d482e-2a76-47be-8fff-1227d0ce403d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_b9a213cb-3f88-42dc-ba30-a0f82f999039" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_3a2d482e-2a76-47be-8fff-1227d0ce403d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_2559acaf-b6f5-4745-8a1f-1e5f454d5bd2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_3a2d482e-2a76-47be-8fff-1227d0ce403d" xlink:to="loc_us-gaap_NoncontrollingInterestMember_2559acaf-b6f5-4745-8a1f-1e5f454d5bd2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_41764ffd-ea68-4513-a489-055a0df2e61a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_681a2219-1e77-4142-8fd0-4583cc5eec2f" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_41764ffd-ea68-4513-a489-055a0df2e61a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_41764ffd-ea68-4513-a489-055a0df2e61a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_41764ffd-ea68-4513-a489-055a0df2e61a" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_41764ffd-ea68-4513-a489-055a0df2e61a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_39648f93-6aad-4519-8597-34465e4f8bfe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_41764ffd-ea68-4513-a489-055a0df2e61a" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_39648f93-6aad-4519-8597-34465e4f8bfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainslossesOnInvestmentsInUnconsolidatedEntitiesNetMember_3e9a754e-5c2f-4172-abd4-70bc2802ed68" xlink:href="pagp-20231231.xsd#pagp_GainslossesOnInvestmentsInUnconsolidatedEntitiesNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_39648f93-6aad-4519-8597-34465e4f8bfe" xlink:to="loc_pagp_GainslossesOnInvestmentsInUnconsolidatedEntitiesNetMember_3e9a754e-5c2f-4172-abd4-70bc2802ed68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_0733cd4c-3786-4e7d-b5e2-e8fff7a5ca30" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_0733cd4c-3786-4e7d-b5e2-e8fff7a5ca30" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_3f4b732d-a6af-473e-9d83-5ed60e1b4687" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_3f4b732d-a6af-473e-9d83-5ed60e1b4687" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage_be0fe383-f215-44f0-850f-8d387c90ee25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage_be0fe383-f215-44f0-850f-8d387c90ee25" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_a7c7fd4d-8ba0-41a1-9cc7-f21aaee49c0d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_a7c7fd4d-8ba0-41a1-9cc7-f21aaee49c0d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_79621b54-a6d3-40ac-be0c-0c0a3701b120" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_79621b54-a6d3-40ac-be0c-0c0a3701b120" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_3de5d41b-29a7-4cfe-9681-5629e7b4c833" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_3de5d41b-29a7-4cfe-9681-5629e7b4c833" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireePercentage_8572d322-2f7d-435c-879c-a6bb7cbe0571" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireePercentage_8572d322-2f7d-435c-879c-a6bb7cbe0571" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1_fcef7ceb-450b-4175-afb4-a5cd947e691c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1_fcef7ceb-450b-4175-afb4-a5cd947e691c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BusinessCombinationMeasurementInput_42ef9133-1e5a-432f-98d6-65c5513d0537" xlink:href="pagp-20231231.xsd#pagp_BusinessCombinationMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_pagp_BusinessCombinationMeasurementInput_42ef9133-1e5a-432f-98d6-65c5513d0537" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain_b36aac72-9adc-4eea-8581-3bb06b5933a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain_b36aac72-9adc-4eea-8581-3bb06b5933a6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_bf25f9be-00a0-4fee-b030-179696f29c5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d5e03866-db86-4238-a791-b96251392108" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_bf25f9be-00a0-4fee-b030-179696f29c5d" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsOtherAcquisitionsNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsOtherAcquisitionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsOtherAcquisitionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2c3104e1-6240-4681-9f63-78d43bf96c57" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2c3104e1-6240-4681-9f63-78d43bf96c57" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_29efa548-f4a2-45f2-8c4b-7aed6655d54e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2c3104e1-6240-4681-9f63-78d43bf96c57" xlink:to="loc_srt_CounterpartyNameAxis_29efa548-f4a2-45f2-8c4b-7aed6655d54e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_29efa548-f4a2-45f2-8c4b-7aed6655d54e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_29efa548-f4a2-45f2-8c4b-7aed6655d54e" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_29efa548-f4a2-45f2-8c4b-7aed6655d54e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_659142f8-fa04-40fe-8481-675cc8cf8ea6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_29efa548-f4a2-45f2-8c4b-7aed6655d54e" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_659142f8-fa04-40fe-8481-675cc8cf8ea6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SubsidiaryOfLMEnergyPartnersMember_ee214edc-8e74-42b2-bcc6-689b5dbc1297" xlink:href="pagp-20231231.xsd#pagp_SubsidiaryOfLMEnergyPartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_659142f8-fa04-40fe-8481-675cc8cf8ea6" xlink:to="loc_pagp_SubsidiaryOfLMEnergyPartnersMember_ee214edc-8e74-42b2-bcc6-689b5dbc1297" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_ddf6215f-de51-4c2a-b91f-48149381871c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2c3104e1-6240-4681-9f63-78d43bf96c57" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_ddf6215f-de51-4c2a-b91f-48149381871c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ddf6215f-de51-4c2a-b91f-48149381871c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_ddf6215f-de51-4c2a-b91f-48149381871c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ddf6215f-de51-4c2a-b91f-48149381871c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f1b1d078-eab3-406b-9b1e-8f39ab407824" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_ddf6215f-de51-4c2a-b91f-48149381871c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f1b1d078-eab3-406b-9b1e-8f39ab407824" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NorthernDelawareBasinGatheringSystemMember_39dcff00-9167-4b1e-a9d3-d06fcf0f06a9" xlink:href="pagp-20231231.xsd#pagp_NorthernDelawareBasinGatheringSystemMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f1b1d078-eab3-406b-9b1e-8f39ab407824" xlink:to="loc_pagp_NorthernDelawareBasinGatheringSystemMember_39dcff00-9167-4b1e-a9d3-d06fcf0f06a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AdvantagePipelineHoldingsLLCMember_785eb8c1-5389-4b94-bb8f-913785e096d6" xlink:href="pagp-20231231.xsd#pagp_AdvantagePipelineHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f1b1d078-eab3-406b-9b1e-8f39ab407824" xlink:to="loc_pagp_AdvantagePipelineHoldingsLLCMember_785eb8c1-5389-4b94-bb8f-913785e096d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_97aecdbd-b886-4062-8ddc-18bec22f195a" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2c3104e1-6240-4681-9f63-78d43bf96c57" xlink:to="loc_dei_LegalEntityAxis_97aecdbd-b886-4062-8ddc-18bec22f195a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_97aecdbd-b886-4062-8ddc-18bec22f195a_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_97aecdbd-b886-4062-8ddc-18bec22f195a" xlink:to="loc_dei_EntityDomain_97aecdbd-b886-4062-8ddc-18bec22f195a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_c917a681-9340-4882-a1b8-c0a5808dc3c1" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_97aecdbd-b886-4062-8ddc-18bec22f195a" xlink:to="loc_dei_EntityDomain_c917a681-9340-4882-a1b8-c0a5808dc3c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_571422cb-875b-4bcb-bf85-065fe5fb4428" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_c917a681-9340-4882-a1b8-c0a5808dc3c1" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_571422cb-875b-4bcb-bf85-065fe5fb4428" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionAxis_6c8b397e-d25b-432c-b078-d0d524a945a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2c3104e1-6240-4681-9f63-78d43bf96c57" xlink:to="loc_us-gaap_AssetAcquisitionAxis_6c8b397e-d25b-432c-b078-d0d524a945a9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_6c8b397e-d25b-432c-b078-d0d524a945a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetAcquisitionAxis_6c8b397e-d25b-432c-b078-d0d524a945a9" xlink:to="loc_us-gaap_AssetAcquisitionDomain_6c8b397e-d25b-432c-b078-d0d524a945a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_a2d00082-648a-472e-8b98-61b76d30b081" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetAcquisitionAxis_6c8b397e-d25b-432c-b078-d0d524a945a9" xlink:to="loc_us-gaap_AssetAcquisitionDomain_a2d00082-648a-472e-8b98-61b76d30b081" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CertainStraddlePlantsMember_af39661e-2abc-4e0f-b936-0f09ac3c7e8e" xlink:href="pagp-20231231.xsd#pagp_CertainStraddlePlantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_a2d00082-648a-472e-8b98-61b76d30b081" xlink:to="loc_pagp_CertainStraddlePlantsMember_af39661e-2abc-4e0f-b936-0f09ac3c7e8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NorthernDelawareBasinGatheringSystemMember_b590af4f-3a52-449b-8798-69aef28c85fd" xlink:href="pagp-20231231.xsd#pagp_NorthernDelawareBasinGatheringSystemMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_a2d00082-648a-472e-8b98-61b76d30b081" xlink:to="loc_pagp_NorthernDelawareBasinGatheringSystemMember_b590af4f-3a52-449b-8798-69aef28c85fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_38532c3d-b938-4f52-bc7f-e77b3a7290ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2c3104e1-6240-4681-9f63-78d43bf96c57" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_38532c3d-b938-4f52-bc7f-e77b3a7290ae" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_38532c3d-b938-4f52-bc7f-e77b3a7290ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_38532c3d-b938-4f52-bc7f-e77b3a7290ae" xlink:to="loc_us-gaap_SegmentDomain_38532c3d-b938-4f52-bc7f-e77b3a7290ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_aded539a-01cf-468b-b799-20b1754753bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_38532c3d-b938-4f52-bc7f-e77b3a7290ae" xlink:to="loc_us-gaap_SegmentDomain_aded539a-01cf-468b-b799-20b1754753bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NaturalGasLiquidsSegmentMember_d716601b-8f51-498d-90d8-ef0616c7c20d" xlink:href="pagp-20231231.xsd#pagp_NaturalGasLiquidsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_aded539a-01cf-468b-b799-20b1754753bf" xlink:to="loc_pagp_NaturalGasLiquidsSegmentMember_d716601b-8f51-498d-90d8-ef0616c7c20d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_c08d6475-67d5-4a7e-baf7-dbe25bcad740" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2c3104e1-6240-4681-9f63-78d43bf96c57" xlink:to="loc_srt_OwnershipAxis_c08d6475-67d5-4a7e-baf7-dbe25bcad740" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_c08d6475-67d5-4a7e-baf7-dbe25bcad740_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_c08d6475-67d5-4a7e-baf7-dbe25bcad740" xlink:to="loc_srt_OwnershipDomain_c08d6475-67d5-4a7e-baf7-dbe25bcad740_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_ecd060c3-564b-4db4-b331-92deaada54d3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_c08d6475-67d5-4a7e-baf7-dbe25bcad740" xlink:to="loc_srt_OwnershipDomain_ecd060c3-564b-4db4-b331-92deaada54d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_39d1c111-e909-40a9-83cf-4ac1aadd5829" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_ecd060c3-564b-4db4-b331-92deaada54d3" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_39d1c111-e909-40a9-83cf-4ac1aadd5829" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_d069c172-999f-4ea1-a3d1-2a6ca617b208" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_d069c172-999f-4ea1-a3d1-2a6ca617b208" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BusinessCombinationConsiderationTransferredNetToOwnershipInterest_db5ca70d-3f70-49d8-95b3-e4ef3cede3e8" xlink:href="pagp-20231231.xsd#pagp_BusinessCombinationConsiderationTransferredNetToOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_pagp_BusinessCombinationConsiderationTransferredNetToOwnershipInterest_db5ca70d-3f70-49d8-95b3-e4ef3cede3e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_763e2f3b-e672-47dd-9662-46f16e51df63" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_763e2f3b-e672-47dd-9662-46f16e51df63" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_0f5cc916-c728-46de-a173-654f17068531" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_0f5cc916-c728-46de-a173-654f17068531" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage_911d9cbd-137f-4b04-b10f-336d84e60f28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage_911d9cbd-137f-4b04-b10f-336d84e60f28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ObligationProcessingCapacityTerm_de4c9395-0f34-4a18-878c-150b103b2a1b" xlink:href="pagp-20231231.xsd#pagp_ObligationProcessingCapacityTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_pagp_ObligationProcessingCapacityTerm_de4c9395-0f34-4a18-878c-150b103b2a1b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferred_6c00e81a-aeef-4d38-a3f2-12d46028a70e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferred_6c00e81a-aeef-4d38-a3f2-12d46028a70e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractWithCustomerLiabilityRevenueRecognitionTerm_38fe5f08-c143-4e67-ba15-a1e455c6bfbc" xlink:href="pagp-20231231.xsd#pagp_ContractWithCustomerLiabilityRevenueRecognitionTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_pagp_ContractWithCustomerLiabilityRevenueRecognitionTerm_38fe5f08-c143-4e67-ba15-a1e455c6bfbc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AssetAcquisitionConsiderationTransferredNetToOwnershipInterest_ead97d26-a8fb-44e9-ba56-73c2211e3fc9" xlink:href="pagp-20231231.xsd#pagp_AssetAcquisitionConsiderationTransferredNetToOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d38f5af7-902f-4cea-b463-5c0b6c0349a3" xlink:to="loc_pagp_AssetAcquisitionConsiderationTransferredNetToOwnershipInterest_ead97d26-a8fb-44e9-ba56-73c2211e3fc9" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsAssetExchangeNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsAssetExchangeNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsAssetExchangeNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_bae89877-c792-437a-a760-151c701119b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7f80e67c-4463-4a76-9b54-e79dbcbc2cda" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_bae89877-c792-437a-a760-151c701119b5" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7f80e67c-4463-4a76-9b54-e79dbcbc2cda" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_054eff58-e9c7-4a33-bb1f-c982ba977665" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7f80e67c-4463-4a76-9b54-e79dbcbc2cda" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_054eff58-e9c7-4a33-bb1f-c982ba977665" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_054eff58-e9c7-4a33-bb1f-c982ba977665_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_054eff58-e9c7-4a33-bb1f-c982ba977665" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_054eff58-e9c7-4a33-bb1f-c982ba977665_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01fff584-3a29-4529-8e4f-de48d17eafa7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_054eff58-e9c7-4a33-bb1f-c982ba977665" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01fff584-3a29-4529-8e4f-de48d17eafa7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AdditionalInterestsInStraddlePlantsMember_be200d10-5585-4981-b29f-65cf1629903b" xlink:href="pagp-20231231.xsd#pagp_AdditionalInterestsInStraddlePlantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01fff584-3a29-4529-8e4f-de48d17eafa7" xlink:to="loc_pagp_AdditionalInterestsInStraddlePlantsMember_be200d10-5585-4981-b29f-65cf1629903b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_da79062a-07cf-4f17-be93-720bb8f0389c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7f80e67c-4463-4a76-9b54-e79dbcbc2cda" xlink:to="loc_srt_CounterpartyNameAxis_da79062a-07cf-4f17-be93-720bb8f0389c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_da79062a-07cf-4f17-be93-720bb8f0389c_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_da79062a-07cf-4f17-be93-720bb8f0389c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_da79062a-07cf-4f17-be93-720bb8f0389c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_831e5328-9365-4c6a-bfc6-35c0cf53193e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_da79062a-07cf-4f17-be93-720bb8f0389c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_831e5328-9365-4c6a-bfc6-35c0cf53193e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InterPipelineLtdMember_727bc815-5876-4eda-9c28-bb595e679dfa" xlink:href="pagp-20231231.xsd#pagp_InterPipelineLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_831e5328-9365-4c6a-bfc6-35c0cf53193e" xlink:to="loc_pagp_InterPipelineLtdMember_727bc815-5876-4eda-9c28-bb595e679dfa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_b711cde8-1bd9-4b67-b985-d56641bfa108" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7f80e67c-4463-4a76-9b54-e79dbcbc2cda" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_b711cde8-1bd9-4b67-b985-d56641bfa108" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_b711cde8-1bd9-4b67-b985-d56641bfa108_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_b711cde8-1bd9-4b67-b985-d56641bfa108" xlink:to="loc_us-gaap_SegmentDomain_b711cde8-1bd9-4b67-b985-d56641bfa108_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_c7293c78-9c30-41cb-beab-58049faa0bf8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_b711cde8-1bd9-4b67-b985-d56641bfa108" xlink:to="loc_us-gaap_SegmentDomain_c7293c78-9c30-41cb-beab-58049faa0bf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NaturalGasLiquidsSegmentMember_efb5fc0e-1e81-4cf4-96b5-dc2bfac19590" xlink:href="pagp-20231231.xsd#pagp_NaturalGasLiquidsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_c7293c78-9c30-41cb-beab-58049faa0bf8" xlink:to="loc_pagp_NaturalGasLiquidsSegmentMember_efb5fc0e-1e81-4cf4-96b5-dc2bfac19590" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_96f20320-2a00-4123-991b-268d3db4492d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7f80e67c-4463-4a76-9b54-e79dbcbc2cda" xlink:to="loc_us-gaap_TransactionTypeAxis_96f20320-2a00-4123-991b-268d3db4492d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_96f20320-2a00-4123-991b-268d3db4492d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_96f20320-2a00-4123-991b-268d3db4492d" xlink:to="loc_us-gaap_TransactionDomain_96f20320-2a00-4123-991b-268d3db4492d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_6e859d26-ca1f-4e25-a2c2-217b2a78ef9d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_96f20320-2a00-4123-991b-268d3db4492d" xlink:to="loc_us-gaap_TransactionDomain_6e859d26-ca1f-4e25-a2c2-217b2a78ef9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AssetExchangeTransactionMember_ebe28373-9334-4879-8121-939fddd10d84" xlink:href="pagp-20231231.xsd#pagp_AssetExchangeTransactionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_6e859d26-ca1f-4e25-a2c2-217b2a78ef9d" xlink:to="loc_pagp_AssetExchangeTransactionMember_ebe28373-9334-4879-8121-939fddd10d84" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_6806b09e-6b07-41fd-ac80-cfea5a3a05fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7f80e67c-4463-4a76-9b54-e79dbcbc2cda" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_6806b09e-6b07-41fd-ac80-cfea5a3a05fe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_6806b09e-6b07-41fd-ac80-cfea5a3a05fe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_6806b09e-6b07-41fd-ac80-cfea5a3a05fe" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_6806b09e-6b07-41fd-ac80-cfea5a3a05fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_ff6ef00b-990c-4109-8620-71dd8265fbc6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_6806b09e-6b07-41fd-ac80-cfea5a3a05fe" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_ff6ef00b-990c-4109-8620-71dd8265fbc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainsLossesOnAssetSalesAndAssetImpairmentsNetMember_c01bd1dc-5bc3-4dbf-836d-ef3d899647de" xlink:href="pagp-20231231.xsd#pagp_GainsLossesOnAssetSalesAndAssetImpairmentsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_ff6ef00b-990c-4109-8620-71dd8265fbc6" xlink:to="loc_pagp_GainsLossesOnAssetSalesAndAssetImpairmentsNetMember_c01bd1dc-5bc3-4dbf-836d-ef3d899647de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NumberOfStraddlePlantsAdditionalInterestsAcquired_3932ab75-833a-497f-a9d7-ff3439790f3e" xlink:href="pagp-20231231.xsd#pagp_NumberOfStraddlePlantsAdditionalInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_bae89877-c792-437a-a760-151c701119b5" xlink:to="loc_pagp_NumberOfStraddlePlantsAdditionalInterestsAcquired_3932ab75-833a-497f-a9d7-ff3439790f3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_03390638-8678-4aef-841f-0648320a80e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_bae89877-c792-437a-a760-151c701119b5" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_03390638-8678-4aef-841f-0648320a80e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_d910d77a-6623-4829-8c8f-086463075739" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_bae89877-c792-437a-a760-151c701119b5" xlink:to="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_d910d77a-6623-4829-8c8f-086463075739" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsJointVentureTransactionNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsJointVentureTransactionNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsJointVentureTransactionNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_80c7c9ab-860c-409b-bc9c-d03fd908cae1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_srt_CounterpartyNameAxis_80c7c9ab-860c-409b-bc9c-d03fd908cae1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_80c7c9ab-860c-409b-bc9c-d03fd908cae1_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_80c7c9ab-860c-409b-bc9c-d03fd908cae1" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_80c7c9ab-860c-409b-bc9c-d03fd908cae1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_27f7781c-bc83-4d0c-b251-7394207e1145" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_80c7c9ab-860c-409b-bc9c-d03fd908cae1" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_27f7781c-bc83-4d0c-b251-7394207e1145" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_99d21cee-81bc-498b-8df1-b3ea861f2918" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_27f7781c-bc83-4d0c-b251-7394207e1145" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_99d21cee-81bc-498b-8df1-b3ea861f2918" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_StonepeakInfrastructurePartnersMember_746b53a7-cf01-415f-b8f8-810d2ebff881" xlink:href="pagp-20231231.xsd#pagp_StonepeakInfrastructurePartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_27f7781c-bc83-4d0c-b251-7394207e1145" xlink:to="loc_pagp_StonepeakInfrastructurePartnersMember_746b53a7-cf01-415f-b8f8-810d2ebff881" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_84f5c221-7a9d-4bc5-ba0f-a22db36af2a4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_srt_OwnershipAxis_84f5c221-7a9d-4bc5-ba0f-a22db36af2a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_84f5c221-7a9d-4bc5-ba0f-a22db36af2a4_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_84f5c221-7a9d-4bc5-ba0f-a22db36af2a4" xlink:to="loc_srt_OwnershipDomain_84f5c221-7a9d-4bc5-ba0f-a22db36af2a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_6d57e5a2-df75-4fd5-bdb8-e40f560c4eca" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_84f5c221-7a9d-4bc5-ba0f-a22db36af2a4" xlink:to="loc_srt_OwnershipDomain_6d57e5a2-df75-4fd5-bdb8-e40f560c4eca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_3e3d623a-4b5d-44da-b1a1-f0bb436bbcd8" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_6d57e5a2-df75-4fd5-bdb8-e40f560c4eca" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_3e3d623a-4b5d-44da-b1a1-f0bb436bbcd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_e21f997e-8099-4e57-9ed9-bc3e37a481c6" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_6d57e5a2-df75-4fd5-bdb8-e40f560c4eca" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_e21f997e-8099-4e57-9ed9-bc3e37a481c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_a7caabaa-172d-4afb-a7ff-f6b0366392f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_us-gaap_TransactionTypeAxis_a7caabaa-172d-4afb-a7ff-f6b0366392f8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_a7caabaa-172d-4afb-a7ff-f6b0366392f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_a7caabaa-172d-4afb-a7ff-f6b0366392f8" xlink:to="loc_us-gaap_TransactionDomain_a7caabaa-172d-4afb-a7ff-f6b0366392f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_9dc66336-531b-451a-889f-f4d20b8827e9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_a7caabaa-172d-4afb-a7ff-f6b0366392f8" xlink:to="loc_us-gaap_TransactionDomain_9dc66336-531b-451a-889f-f4d20b8827e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_JointVentureFormationMember_d92826b1-73c8-4953-ae79-624744bda6d5" xlink:href="pagp-20231231.xsd#pagp_JointVentureFormationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_9dc66336-531b-451a-889f-f4d20b8827e9" xlink:to="loc_pagp_JointVentureFormationMember_d92826b1-73c8-4953-ae79-624744bda6d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementMember_3e52d28d-9c92-4d17-b960-e52d0dfb5c41" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_9dc66336-531b-451a-889f-f4d20b8827e9" xlink:to="loc_pagp_ModifiedSharingArrangementMember_3e52d28d-9c92-4d17-b960-e52d0dfb5c41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_dae2961b-28e9-446e-a5c5-3a679c4956d3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_dae2961b-28e9-446e-a5c5-3a679c4956d3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dae2961b-28e9-446e-a5c5-3a679c4956d3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_dae2961b-28e9-446e-a5c5-3a679c4956d3" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dae2961b-28e9-446e-a5c5-3a679c4956d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_973b0b2c-58ac-4a12-aeb3-be8978df75a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_dae2961b-28e9-446e-a5c5-3a679c4956d3" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_973b0b2c-58ac-4a12-aeb3-be8978df75a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_3c512d96-de6a-45a9-b1b5-c9691203b8fc" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_973b0b2c-58ac-4a12-aeb3-be8978df75a4" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_3c512d96-de6a-45a9-b1b5-c9691203b8fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_bfd651fe-2e38-4b10-9685-43601f74b963" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_dei_LegalEntityAxis_bfd651fe-2e38-4b10-9685-43601f74b963" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_bfd651fe-2e38-4b10-9685-43601f74b963_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_bfd651fe-2e38-4b10-9685-43601f74b963" xlink:to="loc_dei_EntityDomain_bfd651fe-2e38-4b10-9685-43601f74b963_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_002fd4fe-f886-42d4-b8c6-3b48429c9319" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_bfd651fe-2e38-4b10-9685-43601f74b963" xlink:to="loc_dei_EntityDomain_002fd4fe-f886-42d4-b8c6-3b48429c9319" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_b2350cf4-b3fb-458d-8b3b-e17207f72fc2" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_002fd4fe-f886-42d4-b8c6-3b48429c9319" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_b2350cf4-b3fb-458d-8b3b-e17207f72fc2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_911f1dbd-4b9d-4e68-bceb-75cf7ae142b2" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_002fd4fe-f886-42d4-b8c6-3b48429c9319" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_911f1dbd-4b9d-4e68-bceb-75cf7ae142b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_StonepeakInfrastructurePartnersAffiliatesMember_73c3bb59-3df4-4e25-81fd-51d51b586eff" xlink:href="pagp-20231231.xsd#pagp_StonepeakInfrastructurePartnersAffiliatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_002fd4fe-f886-42d4-b8c6-3b48429c9319" xlink:to="loc_pagp_StonepeakInfrastructurePartnersAffiliatesMember_73c3bb59-3df4-4e25-81fd-51d51b586eff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_08a9f1ac-21a5-434f-a926-bc22532e8da9" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_002fd4fe-f886-42d4-b8c6-3b48429c9319" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_08a9f1ac-21a5-434f-a926-bc22532e8da9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_96c95da7-6d02-4e48-b9aa-1330d75239b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_96c95da7-6d02-4e48-b9aa-1330d75239b5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_96c95da7-6d02-4e48-b9aa-1330d75239b5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_96c95da7-6d02-4e48-b9aa-1330d75239b5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_96c95da7-6d02-4e48-b9aa-1330d75239b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1b18bf20-99ab-4f4d-8eac-066beec5fb51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_96c95da7-6d02-4e48-b9aa-1330d75239b5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1b18bf20-99ab-4f4d-8eac-066beec5fb51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_f9a7ce3f-372f-43de-8b46-7c2fd8ecb888" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1b18bf20-99ab-4f4d-8eac-066beec5fb51" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_f9a7ce3f-372f-43de-8b46-7c2fd8ecb888" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_65991ee5-401b-433b-8cb0-2856103a1f88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_65991ee5-401b-433b-8cb0-2856103a1f88" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_65991ee5-401b-433b-8cb0-2856103a1f88_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_65991ee5-401b-433b-8cb0-2856103a1f88" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_65991ee5-401b-433b-8cb0-2856103a1f88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_700a65d2-5174-4b83-8116-0eb60140913f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_65991ee5-401b-433b-8cb0-2856103a1f88" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_700a65d2-5174-4b83-8116-0eb60140913f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_8a9d22d1-8892-450c-9c21-0b4e4b8930fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_700a65d2-5174-4b83-8116-0eb60140913f" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_8a9d22d1-8892-450c-9c21-0b4e4b8930fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_MeasurementInputMarketMultipleMember_1895240a-7882-4eae-af0f-570bcc3a2a92" xlink:href="pagp-20231231.xsd#pagp_MeasurementInputMarketMultipleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_700a65d2-5174-4b83-8116-0eb60140913f" xlink:to="loc_pagp_MeasurementInputMarketMultipleMember_1895240a-7882-4eae-af0f-570bcc3a2a92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_ff861f7f-02c1-4aa4-b548-00ac5bd5d3d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_us-gaap_ValuationTechniqueAxis_ff861f7f-02c1-4aa4-b548-00ac5bd5d3d6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_ff861f7f-02c1-4aa4-b548-00ac5bd5d3d6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_ff861f7f-02c1-4aa4-b548-00ac5bd5d3d6" xlink:to="loc_us-gaap_ValuationTechniqueDomain_ff861f7f-02c1-4aa4-b548-00ac5bd5d3d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_d6c7b9d9-76f3-4868-ba10-4d95a1967211" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_ff861f7f-02c1-4aa4-b548-00ac5bd5d3d6" xlink:to="loc_us-gaap_ValuationTechniqueDomain_d6c7b9d9-76f3-4868-ba10-4d95a1967211" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_629cb7aa-3927-479c-bc7b-f381b1ac1a04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_d6c7b9d9-76f3-4868-ba10-4d95a1967211" xlink:to="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_629cb7aa-3927-479c-bc7b-f381b1ac1a04" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketApproachValuationTechniqueMember_05d10536-fdc1-44b1-b815-5ae0f73734ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketApproachValuationTechniqueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_d6c7b9d9-76f3-4868-ba10-4d95a1967211" xlink:to="loc_us-gaap_MarketApproachValuationTechniqueMember_05d10536-fdc1-44b1-b815-5ae0f73734ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_578c5b78-e5cd-4d33-82ab-b6001038d50d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_srt_RangeAxis_578c5b78-e5cd-4d33-82ab-b6001038d50d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_578c5b78-e5cd-4d33-82ab-b6001038d50d_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_578c5b78-e5cd-4d33-82ab-b6001038d50d" xlink:to="loc_srt_RangeMember_578c5b78-e5cd-4d33-82ab-b6001038d50d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3e5bd19b-15ff-4288-acfe-fbe4b5146cc2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_578c5b78-e5cd-4d33-82ab-b6001038d50d" xlink:to="loc_srt_RangeMember_3e5bd19b-15ff-4288-acfe-fbe4b5146cc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_d3961c7e-f643-4237-82a6-71520399105b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3e5bd19b-15ff-4288-acfe-fbe4b5146cc2" xlink:to="loc_srt_MinimumMember_d3961c7e-f643-4237-82a6-71520399105b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_46501e76-c47e-48e4-904d-8f37e1e5eb06" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3e5bd19b-15ff-4288-acfe-fbe4b5146cc2" xlink:to="loc_srt_MaximumMember_46501e76-c47e-48e4-904d-8f37e1e5eb06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_954e4b1f-078f-4776-8443-6e910ece1ad2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_954e4b1f-078f-4776-8443-6e910ece1ad2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_954e4b1f-078f-4776-8443-6e910ece1ad2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_954e4b1f-078f-4776-8443-6e910ece1ad2" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_954e4b1f-078f-4776-8443-6e910ece1ad2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_5aefae15-b0cc-4034-a2ab-2371e625e505" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_954e4b1f-078f-4776-8443-6e910ece1ad2" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_5aefae15-b0cc-4034-a2ab-2371e625e505" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMember_a4abb497-29e6-40ab-9e70-9503c4e39541" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_5aefae15-b0cc-4034-a2ab-2371e625e505" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMember_a4abb497-29e6-40ab-9e70-9503c4e39541" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_15336355-d7cd-432f-8532-c06f1c785470" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_15336355-d7cd-432f-8532-c06f1c785470" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_15336355-d7cd-432f-8532-c06f1c785470_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_15336355-d7cd-432f-8532-c06f1c785470" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_15336355-d7cd-432f-8532-c06f1c785470_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_248ea6a1-2091-4ce4-987c-d15e0e7f7763" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_15336355-d7cd-432f-8532-c06f1c785470" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_248ea6a1-2091-4ce4-987c-d15e0e7f7763" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_5177463d-718e-4fb7-acdf-2127a9c8f988" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_248ea6a1-2091-4ce4-987c-d15e0e7f7763" xlink:to="loc_us-gaap_CustomerRelationshipsMember_5177463d-718e-4fb7-acdf-2127a9c8f988" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_c4f2af40-344e-4fe4-b42b-22a82e6409d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_b0a9b2fb-4699-47ab-a648-f99f3dbc38d0" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_c4f2af40-344e-4fe4-b42b-22a82e6409d1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c4f2af40-344e-4fe4-b42b-22a82e6409d1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_c4f2af40-344e-4fe4-b42b-22a82e6409d1" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c4f2af40-344e-4fe4-b42b-22a82e6409d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_be20f110-5520-4943-90a7-26c43ba7dd7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_c4f2af40-344e-4fe4-b42b-22a82e6409d1" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_be20f110-5520-4943-90a7-26c43ba7dd7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeriesAPreferredUnitsMember_e00bdf84-36f1-4c52-b7d1-d22603c64ecc" xlink:href="pagp-20231231.xsd#pagp_SeriesAPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_be20f110-5520-4943-90a7-26c43ba7dd7d" xlink:to="loc_pagp_SeriesAPreferredUnitsMember_e00bdf84-36f1-4c52-b7d1-d22603c64ecc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnerMember_b753422b-b730-42dc-8a15-99d43bdb0f2c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_be20f110-5520-4943-90a7-26c43ba7dd7d" xlink:to="loc_us-gaap_LimitedPartnerMember_b753422b-b730-42dc-8a15-99d43bdb0f2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_f3426be8-9e35-4bbb-8509-622909702584" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_f3426be8-9e35-4bbb-8509-622909702584" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_42362e68-ea40-4c38-a9e7-f48d71a7da2a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_42362e68-ea40-4c38-a9e7-f48d71a7da2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MembersEquity_edb5cbc8-016f-4497-913d-71dceae18e2e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MembersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_us-gaap_MembersEquity_edb5cbc8-016f-4497-913d-71dceae18e2e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_380fba73-b8a4-44fd-9ce5-ff6127124893" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_380fba73-b8a4-44fd-9ce5-ff6127124893" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_6fe7bb99-eae1-47ce-9d09-6f019144cc70" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_6fe7bb99-eae1-47ce-9d09-6f019144cc70" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BusinessCombinationMeasurementInput_9ba4408d-6f75-49da-b4ed-c2ff339ce454" xlink:href="pagp-20231231.xsd#pagp_BusinessCombinationMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_pagp_BusinessCombinationMeasurementInput_9ba4408d-6f75-49da-b4ed-c2ff339ce454" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_e597d6c5-9051-47ce-99aa-73338c3e2638" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_e597d6c5-9051-47ce-99aa-73338c3e2638" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementTerm_9effc541-47ef-4bcb-a2b6-02d96abdf3e8" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_pagp_ModifiedSharingArrangementTerm_9effc541-47ef-4bcb-a2b6-02d96abdf3e8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DistributionPercentageAfterTerminationOfModifiedSharingArrangement_05a2d1e3-b91c-4be1-998c-5e7417c450fd" xlink:href="pagp-20231231.xsd#pagp_DistributionPercentageAfterTerminationOfModifiedSharingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_pagp_DistributionPercentageAfterTerminationOfModifiedSharingArrangement_05a2d1e3-b91c-4be1-998c-5e7417c450fd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest_423fd099-d7d5-46a9-8526-c45ef018421b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_ae9fe020-eb55-4e46-b117-f2bc8d2209ff" xlink:to="loc_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest_423fd099-d7d5-46a9-8526-c45ef018421b" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsPartnersCapitalDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsPartnersCapitalDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsPartnersCapitalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_c9592ca3-c763-47ed-a167-df3637a59d39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_c9592ca3-c763-47ed-a167-df3637a59d39" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_c274f152-0764-4be3-a18e-2cc6f0980f71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_c274f152-0764-4be3-a18e-2cc6f0980f71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c274f152-0764-4be3-a18e-2cc6f0980f71_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_c274f152-0764-4be3-a18e-2cc6f0980f71" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c274f152-0764-4be3-a18e-2cc6f0980f71_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ad0bbdfa-4ae2-4407-ac80-06dc8c026fd5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_c274f152-0764-4be3-a18e-2cc6f0980f71" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ad0bbdfa-4ae2-4407-ac80-06dc8c026fd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_5d27e572-2585-44cd-8ee1-1f253ea6a4f4" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ad0bbdfa-4ae2-4407-ac80-06dc8c026fd5" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_5d27e572-2585-44cd-8ee1-1f253ea6a4f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_efd3aaf0-e8f0-41a3-826d-ee5bc2357eaf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:to="loc_us-gaap_TransactionTypeAxis_efd3aaf0-e8f0-41a3-826d-ee5bc2357eaf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_efd3aaf0-e8f0-41a3-826d-ee5bc2357eaf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_efd3aaf0-e8f0-41a3-826d-ee5bc2357eaf" xlink:to="loc_us-gaap_TransactionDomain_efd3aaf0-e8f0-41a3-826d-ee5bc2357eaf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_b3f51eff-4ad2-493e-be83-dd9085dbe19c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_efd3aaf0-e8f0-41a3-826d-ee5bc2357eaf" xlink:to="loc_us-gaap_TransactionDomain_b3f51eff-4ad2-493e-be83-dd9085dbe19c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_JointVentureFormationMember_6284d6a9-2a90-48ef-84dd-09b97908266c" xlink:href="pagp-20231231.xsd#pagp_JointVentureFormationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_b3f51eff-4ad2-493e-be83-dd9085dbe19c" xlink:to="loc_pagp_JointVentureFormationMember_6284d6a9-2a90-48ef-84dd-09b97908266c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_4ad9b430-af59-44a4-9e8f-2a20a7ab4bde" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:to="loc_dei_LegalEntityAxis_4ad9b430-af59-44a4-9e8f-2a20a7ab4bde" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_4ad9b430-af59-44a4-9e8f-2a20a7ab4bde_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_4ad9b430-af59-44a4-9e8f-2a20a7ab4bde" xlink:to="loc_dei_EntityDomain_4ad9b430-af59-44a4-9e8f-2a20a7ab4bde_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_d8cdad78-5842-4685-9391-d5e0dab8a510" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_4ad9b430-af59-44a4-9e8f-2a20a7ab4bde" xlink:to="loc_dei_EntityDomain_d8cdad78-5842-4685-9391-d5e0dab8a510" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_c8a857e3-6230-4509-8edf-f7981389ba2d" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_d8cdad78-5842-4685-9391-d5e0dab8a510" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_c8a857e3-6230-4509-8edf-f7981389ba2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsAxis_1bb213ad-da98-433d-baeb-ce981a84cad7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:to="loc_us-gaap_PartnerCapitalComponentsAxis_1bb213ad-da98-433d-baeb-ce981a84cad7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_1bb213ad-da98-433d-baeb-ce981a84cad7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_1bb213ad-da98-433d-baeb-ce981a84cad7" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_1bb213ad-da98-433d-baeb-ce981a84cad7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_46ec61ef-e993-4175-829f-3261f8281319" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_1bb213ad-da98-433d-baeb-ce981a84cad7" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_46ec61ef-e993-4175-829f-3261f8281319" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_b8362d28-99ca-4c8d-8ee9-c4495921182d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_46ec61ef-e993-4175-829f-3261f8281319" xlink:to="loc_us-gaap_NoncontrollingInterestMember_b8362d28-99ca-4c8d-8ee9-c4495921182d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_63bdc545-7bb8-4f5d-8458-4fe26a669c9d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:to="loc_srt_OwnershipAxis_63bdc545-7bb8-4f5d-8458-4fe26a669c9d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_63bdc545-7bb8-4f5d-8458-4fe26a669c9d_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_63bdc545-7bb8-4f5d-8458-4fe26a669c9d" xlink:to="loc_srt_OwnershipDomain_63bdc545-7bb8-4f5d-8458-4fe26a669c9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_fe2a56e6-cbee-4fb3-9762-d2a4a3bd4665" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_63bdc545-7bb8-4f5d-8458-4fe26a669c9d" xlink:to="loc_srt_OwnershipDomain_fe2a56e6-cbee-4fb3-9762-d2a4a3bd4665" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_b11e7ab1-6cc8-418e-ae5e-2d2229bb810f" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_fe2a56e6-cbee-4fb3-9762-d2a4a3bd4665" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_b11e7ab1-6cc8-418e-ae5e-2d2229bb810f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_5e5117b3-2fd2-4373-9355-b3dba7ecfc47" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_fe2a56e6-cbee-4fb3-9762-d2a4a3bd4665" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_5e5117b3-2fd2-4373-9355-b3dba7ecfc47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_06fe2144-6d51-41e1-9e5c-b8cfa00ef440" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:to="loc_srt_ConsolidatedEntitiesAxis_06fe2144-6d51-41e1-9e5c-b8cfa00ef440" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_06fe2144-6d51-41e1-9e5c-b8cfa00ef440_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_06fe2144-6d51-41e1-9e5c-b8cfa00ef440" xlink:to="loc_srt_ConsolidatedEntitiesDomain_06fe2144-6d51-41e1-9e5c-b8cfa00ef440_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_a4ea1b90-8364-4651-9109-86000de7a88f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_06fe2144-6d51-41e1-9e5c-b8cfa00ef440" xlink:to="loc_srt_ConsolidatedEntitiesDomain_a4ea1b90-8364-4651-9109-86000de7a88f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_eb17316d-2d1f-41d6-a5ea-52762c5c79a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_a4ea1b90-8364-4651-9109-86000de7a88f" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_eb17316d-2d1f-41d6-a5ea-52762c5c79a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_441bc78a-ca0b-4d1b-84dc-ec48c7196584" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_02989148-0401-4104-a651-6a0cc88f9d9f" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_441bc78a-ca0b-4d1b-84dc-ec48c7196584" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_441bc78a-ca0b-4d1b-84dc-ec48c7196584_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_441bc78a-ca0b-4d1b-84dc-ec48c7196584" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_441bc78a-ca0b-4d1b-84dc-ec48c7196584_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_086beccc-9eda-4544-8fb9-071884cadd88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_441bc78a-ca0b-4d1b-84dc-ec48c7196584" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_086beccc-9eda-4544-8fb9-071884cadd88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_022446d9-7839-4cbc-8e9d-fe3d6125e6dd" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_086beccc-9eda-4544-8fb9-071884cadd88" xlink:to="loc_pagp_SharesClassAMember_022446d9-7839-4cbc-8e9d-fe3d6125e6dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_1ca9f61e-fcaf-4e8c-9e2a-9fc0e368e260" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_c9592ca3-c763-47ed-a167-df3637a59d39" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_1ca9f61e-fcaf-4e8c-9e2a-9fc0e368e260" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_18c078f5-2ecb-41f6-8a10-05dcf102ba51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_c9592ca3-c763-47ed-a167-df3637a59d39" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_18c078f5-2ecb-41f6-8a10-05dcf102ba51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountAcquisitions_1223decc-41e9-423b-99f7-c65a67dba88c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_c9592ca3-c763-47ed-a167-df3637a59d39" xlink:to="loc_us-gaap_PartnersCapitalAccountAcquisitions_1223decc-41e9-423b-99f7-c65a67dba88c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsModifiedSharingArrangementDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsModifiedSharingArrangementDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsModifiedSharingArrangementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_70ad77d4-5168-4720-87e0-b4f053a38a88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d4d620c6-be12-42de-afc7-fa6418a58f5f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70ad77d4-5168-4720-87e0-b4f053a38a88" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d4d620c6-be12-42de-afc7-fa6418a58f5f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_cdf8f0ee-5a2b-4424-8049-2c2f84791b52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d4d620c6-be12-42de-afc7-fa6418a58f5f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_cdf8f0ee-5a2b-4424-8049-2c2f84791b52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_cdf8f0ee-5a2b-4424-8049-2c2f84791b52_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_cdf8f0ee-5a2b-4424-8049-2c2f84791b52" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_cdf8f0ee-5a2b-4424-8049-2c2f84791b52_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6d2425cc-9939-4dc7-bd46-d0c2adb579d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_cdf8f0ee-5a2b-4424-8049-2c2f84791b52" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6d2425cc-9939-4dc7-bd46-d0c2adb579d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_8f4831f2-4eb5-4e09-932a-710b3543c6f8" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6d2425cc-9939-4dc7-bd46-d0c2adb579d4" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_8f4831f2-4eb5-4e09-932a-710b3543c6f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_3653af06-b051-4e0e-b327-2a9a407148fd" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d4d620c6-be12-42de-afc7-fa6418a58f5f" xlink:to="loc_dei_LegalEntityAxis_3653af06-b051-4e0e-b327-2a9a407148fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_3653af06-b051-4e0e-b327-2a9a407148fd_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_3653af06-b051-4e0e-b327-2a9a407148fd" xlink:to="loc_dei_EntityDomain_3653af06-b051-4e0e-b327-2a9a407148fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_f40edd47-74ba-423d-aa0f-f8a7f8bc1ca5" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_3653af06-b051-4e0e-b327-2a9a407148fd" xlink:to="loc_dei_EntityDomain_f40edd47-74ba-423d-aa0f-f8a7f8bc1ca5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_0f6a26a3-2188-465d-9d34-1305d6ed5da1" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_f40edd47-74ba-423d-aa0f-f8a7f8bc1ca5" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_0f6a26a3-2188-465d-9d34-1305d6ed5da1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_8019ebda-aaa0-4ec0-b0cb-4aec8dbc0be4" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_f40edd47-74ba-423d-aa0f-f8a7f8bc1ca5" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_8019ebda-aaa0-4ec0-b0cb-4aec8dbc0be4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_ee5d102c-26f1-4295-86dc-dad6f66066a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d4d620c6-be12-42de-afc7-fa6418a58f5f" xlink:to="loc_us-gaap_TransactionTypeAxis_ee5d102c-26f1-4295-86dc-dad6f66066a9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_ee5d102c-26f1-4295-86dc-dad6f66066a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_ee5d102c-26f1-4295-86dc-dad6f66066a9" xlink:to="loc_us-gaap_TransactionDomain_ee5d102c-26f1-4295-86dc-dad6f66066a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_7f4f52f3-0943-4a2b-b691-28259a217f89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_ee5d102c-26f1-4295-86dc-dad6f66066a9" xlink:to="loc_us-gaap_TransactionDomain_7f4f52f3-0943-4a2b-b691-28259a217f89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementMember_337727e2-0070-420d-9da8-efa1c0a50e9d" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_7f4f52f3-0943-4a2b-b691-28259a217f89" xlink:to="loc_pagp_ModifiedSharingArrangementMember_337727e2-0070-420d-9da8-efa1c0a50e9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashAxis_09055d94-2029-4370-a27e-81347c6a5029" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementAnnualAvailableCashAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_d4d620c6-be12-42de-afc7-fa6418a58f5f" xlink:to="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashAxis_09055d94-2029-4370-a27e-81347c6a5029" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashDomain_09055d94-2029-4370-a27e-81347c6a5029_default" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementAnnualAvailableCashDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashAxis_09055d94-2029-4370-a27e-81347c6a5029" xlink:to="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashDomain_09055d94-2029-4370-a27e-81347c6a5029_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashDomain_cf816c70-db4f-47d0-bd99-b6a18d6814e9" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementAnnualAvailableCashDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashAxis_09055d94-2029-4370-a27e-81347c6a5029" xlink:to="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashDomain_cf816c70-db4f-47d0-bd99-b6a18d6814e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashUpTo300MillionMember_895800ae-c3b0-4361-b39a-4c960e31c5d8" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementAnnualAvailableCashUpTo300MillionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashDomain_cf816c70-db4f-47d0-bd99-b6a18d6814e9" xlink:to="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashUpTo300MillionMember_895800ae-c3b0-4361-b39a-4c960e31c5d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashBetween300MillionTo428MillionMember_4bbcbece-8050-4263-b767-01362c765ce2" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementAnnualAvailableCashBetween300MillionTo428MillionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashDomain_cf816c70-db4f-47d0-bd99-b6a18d6814e9" xlink:to="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashBetween300MillionTo428MillionMember_4bbcbece-8050-4263-b767-01362c765ce2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedRevenueArrangementAnnualAvailableCashBetween428MillionTo815MillionMember_e6964d2c-eba2-4d73-bf70-d5ba35cb38cb" xlink:href="pagp-20231231.xsd#pagp_ModifiedRevenueArrangementAnnualAvailableCashBetween428MillionTo815MillionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashDomain_cf816c70-db4f-47d0-bd99-b6a18d6814e9" xlink:to="loc_pagp_ModifiedRevenueArrangementAnnualAvailableCashBetween428MillionTo815MillionMember_e6964d2c-eba2-4d73-bf70-d5ba35cb38cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementAnnualAvailableCash815MillionAndAboveMember_81aa1ce1-c55c-4415-808e-309bb32e9b81" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementAnnualAvailableCash815MillionAndAboveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ModifiedSharingArrangementAnnualAvailableCashDomain_cf816c70-db4f-47d0-bd99-b6a18d6814e9" xlink:to="loc_pagp_ModifiedSharingArrangementAnnualAvailableCash815MillionAndAboveMember_81aa1ce1-c55c-4415-808e-309bb32e9b81" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ModifiedSharingArrangementDistributionPercentage_df0bce29-b828-4f6d-b4bd-632a9f7659ed" xlink:href="pagp-20231231.xsd#pagp_ModifiedSharingArrangementDistributionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_70ad77d4-5168-4720-87e0-b4f053a38a88" xlink:to="loc_pagp_ModifiedSharingArrangementDistributionPercentage_df0bce29-b828-4f6d-b4bd-632a9f7659ed" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsProFormaDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsProFormaDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsProFormaDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_2291a557-465f-4d57-a70a-bd0809dc8381" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4d5076aa-bf71-4efa-846b-845d26967829" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2291a557-465f-4d57-a70a-bd0809dc8381" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4d5076aa-bf71-4efa-846b-845d26967829" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_5f210946-62ed-4273-8211-762c34d3b04a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4d5076aa-bf71-4efa-846b-845d26967829" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_5f210946-62ed-4273-8211-762c34d3b04a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5f210946-62ed-4273-8211-762c34d3b04a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5f210946-62ed-4273-8211-762c34d3b04a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5f210946-62ed-4273-8211-762c34d3b04a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_117abea9-c374-44b6-b464-35f23df3fed3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5f210946-62ed-4273-8211-762c34d3b04a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_117abea9-c374-44b6-b464-35f23df3fed3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_1158247d-c62c-4a1d-8dc2-ee1ae9ae5465" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_117abea9-c374-44b6-b464-35f23df3fed3" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_1158247d-c62c-4a1d-8dc2-ee1ae9ae5465" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_bdf959d0-06eb-48b3-a552-350542a169cd" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4d5076aa-bf71-4efa-846b-845d26967829" xlink:to="loc_srt_CounterpartyNameAxis_bdf959d0-06eb-48b3-a552-350542a169cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_bdf959d0-06eb-48b3-a552-350542a169cd_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_bdf959d0-06eb-48b3-a552-350542a169cd" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_bdf959d0-06eb-48b3-a552-350542a169cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_f2210aa9-f825-4cf3-a63a-3080cb14f2c7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_bdf959d0-06eb-48b3-a552-350542a169cd" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_f2210aa9-f825-4cf3-a63a-3080cb14f2c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_92294dad-e2a1-4371-ab23-8b758c0a11e4" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_f2210aa9-f825-4cf3-a63a-3080cb14f2c7" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_92294dad-e2a1-4371-ab23-8b758c0a11e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_1342d1ce-2519-4464-9c99-681707540d7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4d5076aa-bf71-4efa-846b-845d26967829" xlink:to="loc_us-gaap_TransactionTypeAxis_1342d1ce-2519-4464-9c99-681707540d7e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_1342d1ce-2519-4464-9c99-681707540d7e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_1342d1ce-2519-4464-9c99-681707540d7e" xlink:to="loc_us-gaap_TransactionDomain_1342d1ce-2519-4464-9c99-681707540d7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_e940195a-f8bd-410e-88a6-521f120ebeb6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_1342d1ce-2519-4464-9c99-681707540d7e" xlink:to="loc_us-gaap_TransactionDomain_e940195a-f8bd-410e-88a6-521f120ebeb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_JointVentureFormationMember_85ebabee-594e-47fd-9910-ac1f16a9a6e1" xlink:href="pagp-20231231.xsd#pagp_JointVentureFormationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_e940195a-f8bd-410e-88a6-521f120ebeb6" xlink:to="loc_pagp_JointVentureFormationMember_85ebabee-594e-47fd-9910-ac1f16a9a6e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_49c1c90a-729e-4c86-8311-117025f801bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4d5076aa-bf71-4efa-846b-845d26967829" xlink:to="loc_us-gaap_StatementClassOfStockAxis_49c1c90a-729e-4c86-8311-117025f801bb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_49c1c90a-729e-4c86-8311-117025f801bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_49c1c90a-729e-4c86-8311-117025f801bb" xlink:to="loc_us-gaap_ClassOfStockDomain_49c1c90a-729e-4c86-8311-117025f801bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_8c4e9020-0486-43f2-b672-cbf92f440f58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_49c1c90a-729e-4c86-8311-117025f801bb" xlink:to="loc_us-gaap_ClassOfStockDomain_8c4e9020-0486-43f2-b672-cbf92f440f58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_687b9f2c-fa5c-4c3b-8ff3-f2f27e8a519d" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_8c4e9020-0486-43f2-b672-cbf92f440f58" xlink:to="loc_pagp_SharesClassAMember_687b9f2c-fa5c-4c3b-8ff3-f2f27e8a519d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_36659b35-0031-4a50-a831-0c2136ac43de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2291a557-465f-4d57-a70a-bd0809dc8381" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_36659b35-0031-4a50-a831-0c2136ac43de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BusinessCombinationProFormaNetIncomeLossAttributableToTheParent_603353cf-06fe-4341-a02f-08613ef49a25" xlink:href="pagp-20231231.xsd#pagp_BusinessCombinationProFormaNetIncomeLossAttributableToTheParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2291a557-465f-4d57-a70a-bd0809dc8381" xlink:to="loc_pagp_BusinessCombinationProFormaNetIncomeLossAttributableToTheParent_603353cf-06fe-4341-a02f-08613ef49a25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_4ddc86f0-c0fb-403c-87be-c827d55f5634" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2291a557-465f-4d57-a70a-bd0809dc8381" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_4ddc86f0-c0fb-403c-87be-c827d55f5634" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_9bd0fb09-b260-40c6-bdaa-f23d94ba6d20" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2291a557-465f-4d57-a70a-bd0809dc8381" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_9bd0fb09-b260-40c6-bdaa-f23d94ba6d20" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsDivestituresNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#AcquisitionsDivestituresandOtherTransactionsDivestituresNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/AcquisitionsDivestituresandOtherTransactionsDivestituresNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_0969e650-5837-42e6-a5e2-edc8d5acf5ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_0969e650-5837-42e6-a5e2-edc8d5acf5ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0969e650-5837-42e6-a5e2-edc8d5acf5ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0969e650-5837-42e6-a5e2-edc8d5acf5ba" xlink:to="loc_us-gaap_SegmentDomain_0969e650-5837-42e6-a5e2-edc8d5acf5ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_3a9b999e-83dc-4795-a8e3-684d4c41f32c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0969e650-5837-42e6-a5e2-edc8d5acf5ba" xlink:to="loc_us-gaap_SegmentDomain_3a9b999e-83dc-4795-a8e3-684d4c41f32c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilSegmentMember_5e0b3ef5-773f-40c2-8cc3-5aea9a539915" xlink:href="pagp-20231231.xsd#pagp_CrudeOilSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3a9b999e-83dc-4795-a8e3-684d4c41f32c" xlink:to="loc_pagp_CrudeOilSegmentMember_5e0b3ef5-773f-40c2-8cc3-5aea9a539915" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_397f635f-a441-49e9-9c01-fed16c4317a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_397f635f-a441-49e9-9c01-fed16c4317a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_397f635f-a441-49e9-9c01-fed16c4317a7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_397f635f-a441-49e9-9c01-fed16c4317a7" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_397f635f-a441-49e9-9c01-fed16c4317a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_f2d6b0bc-8cd0-4f39-902e-e44e59c3849e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_397f635f-a441-49e9-9c01-fed16c4317a7" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_f2d6b0bc-8cd0-4f39-902e-e44e59c3849e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AssetsSoldPrimarilyConsistedOfLandAndRelatedAssetsInLongBeachCaliforniaAsWellAsLine901AndTheSisquocToPentlandPortionOfLine903Member_f21f8fd4-7da6-4888-b3de-752a4c550000" xlink:href="pagp-20231231.xsd#pagp_AssetsSoldPrimarilyConsistedOfLandAndRelatedAssetsInLongBeachCaliforniaAsWellAsLine901AndTheSisquocToPentlandPortionOfLine903Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_f2d6b0bc-8cd0-4f39-902e-e44e59c3849e" xlink:to="loc_pagp_AssetsSoldPrimarilyConsistedOfLandAndRelatedAssetsInLongBeachCaliforniaAsWellAsLine901AndTheSisquocToPentlandPortionOfLine903Member_f21f8fd4-7da6-4888-b3de-752a4c550000" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PinePrairieAndSouthernPinesNaturalGasStorageFacilitiesMember_57f7edb9-281e-423a-9623-fcb9f0ec2d7b" xlink:href="pagp-20231231.xsd#pagp_PinePrairieAndSouthernPinesNaturalGasStorageFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_f2d6b0bc-8cd0-4f39-902e-e44e59c3849e" xlink:to="loc_pagp_PinePrairieAndSouthernPinesNaturalGasStorageFacilitiesMember_57f7edb9-281e-423a-9623-fcb9f0ec2d7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_7dff22bf-b120-4613-b3c7-9cb786dccc1d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_7dff22bf-b120-4613-b3c7-9cb786dccc1d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_7dff22bf-b120-4613-b3c7-9cb786dccc1d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_7dff22bf-b120-4613-b3c7-9cb786dccc1d" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_7dff22bf-b120-4613-b3c7-9cb786dccc1d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_6bae1fd6-6efe-4c06-8d1a-7a4a9a580f2d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_7dff22bf-b120-4613-b3c7-9cb786dccc1d" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_6bae1fd6-6efe-4c06-8d1a-7a4a9a580f2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_b0d28939-2b3b-4b85-a782-cfbc82bd3351" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_6bae1fd6-6efe-4c06-8d1a-7a4a9a580f2d" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_b0d28939-2b3b-4b85-a782-cfbc82bd3351" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember_67ca7a33-469b-4441-b3b6-ee7e02d35c82" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_6bae1fd6-6efe-4c06-8d1a-7a4a9a580f2d" xlink:to="loc_us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember_67ca7a33-469b-4441-b3b6-ee7e02d35c82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsAxis_ab6252e5-2f5c-42bb-ab18-3257614095be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:to="loc_us-gaap_PartnerCapitalComponentsAxis_ab6252e5-2f5c-42bb-ab18-3257614095be" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_ab6252e5-2f5c-42bb-ab18-3257614095be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_ab6252e5-2f5c-42bb-ab18-3257614095be" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_ab6252e5-2f5c-42bb-ab18-3257614095be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_e256e772-b56a-4ce0-a503-7e29edc4715a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_ab6252e5-2f5c-42bb-ab18-3257614095be" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_e256e772-b56a-4ce0-a503-7e29edc4715a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember_d0fbcc19-cd95-4b93-a601-3fbd696e8c98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_e256e772-b56a-4ce0-a503-7e29edc4715a" xlink:to="loc_us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember_d0fbcc19-cd95-4b93-a601-3fbd696e8c98" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_bdba6e9d-e8c5-41dc-b3a0-b266f886e8e9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_bdba6e9d-e8c5-41dc-b3a0-b266f886e8e9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_bdba6e9d-e8c5-41dc-b3a0-b266f886e8e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_bdba6e9d-e8c5-41dc-b3a0-b266f886e8e9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_bdba6e9d-e8c5-41dc-b3a0-b266f886e8e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_cb88a498-553e-4c4a-a360-7ae521f14e46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_bdba6e9d-e8c5-41dc-b3a0-b266f886e8e9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_cb88a498-553e-4c4a-a360-7ae521f14e46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainsLossesOnAssetSalesAndAssetImpairmentsNetMember_21830eb7-2742-428f-bc21-ce8ec58fac4c" xlink:href="pagp-20231231.xsd#pagp_GainsLossesOnAssetSalesAndAssetImpairmentsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_cb88a498-553e-4c4a-a360-7ae521f14e46" xlink:to="loc_pagp_GainsLossesOnAssetSalesAndAssetImpairmentsNetMember_21830eb7-2742-428f-bc21-ce8ec58fac4c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis_3ee93633-9635-4570-8dea-b7333cfc1d65" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:to="loc_us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis_3ee93633-9635-4570-8dea-b7333cfc1d65" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongLivedAssetsHeldForSaleNameDomain_3ee93633-9635-4570-8dea-b7333cfc1d65_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongLivedAssetsHeldForSaleNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis_3ee93633-9635-4570-8dea-b7333cfc1d65" xlink:to="loc_us-gaap_LongLivedAssetsHeldForSaleNameDomain_3ee93633-9635-4570-8dea-b7333cfc1d65_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongLivedAssetsHeldForSaleNameDomain_399350b5-2a54-4b04-b237-67e75e6f64bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongLivedAssetsHeldForSaleNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis_3ee93633-9635-4570-8dea-b7333cfc1d65" xlink:to="loc_us-gaap_LongLivedAssetsHeldForSaleNameDomain_399350b5-2a54-4b04-b237-67e75e6f64bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_KeyeraFortSaskatchewanFacilityMember_34e97a6d-22de-43ae-8256-6ea2c8a822b3" xlink:href="pagp-20231231.xsd#pagp_KeyeraFortSaskatchewanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongLivedAssetsHeldForSaleNameDomain_399350b5-2a54-4b04-b237-67e75e6f64bd" xlink:to="loc_pagp_KeyeraFortSaskatchewanFacilityMember_34e97a6d-22de-43ae-8256-6ea2c8a822b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_27646655-3def-4b27-9d59-f3f4554f5c95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_f0650b24-0d7b-4aef-91d9-3391a844f097" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_27646655-3def-4b27-9d59-f3f4554f5c95" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_27646655-3def-4b27-9d59-f3f4554f5c95_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_27646655-3def-4b27-9d59-f3f4554f5c95" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_27646655-3def-4b27-9d59-f3f4554f5c95_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_53c3801d-5553-4d1a-b421-3d800dcd8354" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_27646655-3def-4b27-9d59-f3f4554f5c95" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_53c3801d-5553-4d1a-b421-3d800dcd8354" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_0bbaaa8a-e772-450e-9030-a805b15831aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_53c3801d-5553-4d1a-b421-3d800dcd8354" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_0bbaaa8a-e772-450e-9030-a805b15831aa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NonOperatedUndividedJointInterestOwnershipPercentageSold_7ad2ab70-ebed-4836-8036-dd81c0eb60ae" xlink:href="pagp-20231231.xsd#pagp_NonOperatedUndividedJointInterestOwnershipPercentageSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_pagp_NonOperatedUndividedJointInterestOwnershipPercentageSold_7ad2ab70-ebed-4836-8036-dd81c0eb60ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfInterestInJointVenture_ce5825ff-c88e-4f04-9581-53ed41978687" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromDivestitureOfInterestInJointVenture"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfInterestInJointVenture_ce5825ff-c88e-4f04-9581-53ed41978687" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup_ac4a63e2-c908-40ca-80f6-e661c7574320" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup_ac4a63e2-c908-40ca-80f6-e661c7574320" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_eda81f88-c785-4fcd-91a9-40201a837a11" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_eda81f88-c785-4fcd-91a9-40201a837a11" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfProductiveAssets_8867ae17-c04b-4857-8d47-3243d6606720" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleOfProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_ProceedsFromSaleOfProductiveAssets_8867ae17-c04b-4857-8d47-3243d6606720" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_610990ba-92a7-4461-882c-7a0861e638aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_610990ba-92a7-4461-882c-7a0861e638aa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_0469c277-139e-40e7-9c96-1f1df43cddda" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_0469c277-139e-40e7-9c96-1f1df43cddda" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapital_7d864d13-c2ea-46b8-bb81-c89ce6d204f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_PartnersCapital_7d864d13-c2ea-46b8-bb81-c89ce6d204f6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf_2d60ac5d-4c5e-4219-9af4-317299d249dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_22de39d0-f4f5-429e-a701-055c1f69eb79" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf_2d60ac5d-4c5e-4219-9af4-317299d249dd" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/InvestmentsinUnconsolidatedEntitiesEquityMethodInvestmentsDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#InvestmentsinUnconsolidatedEntitiesEquityMethodInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/InvestmentsinUnconsolidatedEntitiesEquityMethodInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_c9ea0c99-8532-46a0-bd58-9a5eb422d3b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_c9ea0c99-8532-46a0-bd58-9a5eb422d3b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8ceb63fd-d649-40b4-bd02-4929de79e37b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_c9ea0c99-8532-46a0-bd58-9a5eb422d3b0" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8ceb63fd-d649-40b4-bd02-4929de79e37b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_8ceb63fd-d649-40b4-bd02-4929de79e37b_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8ceb63fd-d649-40b4-bd02-4929de79e37b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_8ceb63fd-d649-40b4-bd02-4929de79e37b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8ceb63fd-d649-40b4-bd02-4929de79e37b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BridgeTexPipelineCompanyLLCMember_8a5e859b-125b-4b97-9cdb-c034e4cce8e8" xlink:href="pagp-20231231.xsd#pagp_BridgeTexPipelineCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_BridgeTexPipelineCompanyLLCMember_8a5e859b-125b-4b97-9cdb-c034e4cce8e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CaplinePipelineCompanyLLCMember_10fa6169-97ac-4487-9f64-53a554030ff9" xlink:href="pagp-20231231.xsd#pagp_CaplinePipelineCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_CaplinePipelineCompanyLLCMember_10fa6169-97ac-4487-9f64-53a554030ff9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DiamondPipelineLLCMember_bf91d479-d1cc-4e29-a7a5-adb21721aa89" xlink:href="pagp-20231231.xsd#pagp_DiamondPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_DiamondPipelineLLCMember_bf91d479-d1cc-4e29-a7a5-adb21721aa89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EagleFordPipelineLLCMember_f9436664-3822-41a3-9d1f-f5e40f0ba1dc" xlink:href="pagp-20231231.xsd#pagp_EagleFordPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_EagleFordPipelineLLCMember_f9436664-3822-41a3-9d1f-f5e40f0ba1dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EagleFordTerminalsCorpusChristiLLCMember_e8585bdf-adb2-44ea-806a-9c9c69645f83" xlink:href="pagp-20231231.xsd#pagp_EagleFordTerminalsCorpusChristiLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_EagleFordTerminalsCorpusChristiLLCMember_e8585bdf-adb2-44ea-806a-9c9c69645f83" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OMOGJVLLCMember_62734031-4b8a-4faa-987a-0836169d923f" xlink:href="pagp-20231231.xsd#pagp_OMOGJVLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_OMOGJVLLCMember_62734031-4b8a-4faa-987a-0836169d923f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SaddlehornPipelineCompanyLLCMember_c8eedc1c-7ef8-465d-a38a-c0afa0454897" xlink:href="pagp-20231231.xsd#pagp_SaddlehornPipelineCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_SaddlehornPipelineCompanyLLCMember_c8eedc1c-7ef8-465d-a38a-c0afa0454897" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_WhiteCliffsPipelineLLCMember_38a8e423-001d-4e11-97a0-37c00bf3999d" xlink:href="pagp-20231231.xsd#pagp_WhiteCliffsPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_WhiteCliffsPipelineLLCMember_38a8e423-001d-4e11-97a0-37c00bf3999d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_WinktoWebsterPipelineLLCMember_b4ab9906-a588-41d1-9d0f-e008c05bec89" xlink:href="pagp-20231231.xsd#pagp_WinktoWebsterPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_WinktoWebsterPipelineLLCMember_b4ab9906-a588-41d1-9d0f-e008c05bec89" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OtherEquityMethodInvestmentMember_9d24032b-5b97-4549-bd2c-4b0b7f942ab7" xlink:href="pagp-20231231.xsd#pagp_OtherEquityMethodInvestmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_OtherEquityMethodInvestmentMember_9d24032b-5b97-4549-bd2c-4b0b7f942ab7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AdvantagePipelineHoldingsLLCMember_16c9f2d8-3d78-47ef-b5f2-0d40a9b57874" xlink:href="pagp-20231231.xsd#pagp_AdvantagePipelineHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_AdvantagePipelineHoldingsLLCMember_16c9f2d8-3d78-47ef-b5f2-0d40a9b57874" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_2afd6d89-117e-438a-bdd9-c3f3bcaf001f" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_d50dff80-d22a-4ef2-aa63-496afc8ffe7d" xlink:to="loc_pagp_CactusIIPipelineLLCMember_2afd6d89-117e-438a-bdd9-c3f3bcaf001f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis_8a8e8b8e-7433-419f-89a7-d0ee87041a58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_c9ea0c99-8532-46a0-bd58-9a5eb422d3b0" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis_8a8e8b8e-7433-419f-89a7-d0ee87041a58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_8a8e8b8e-7433-419f-89a7-d0ee87041a58_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncashOrPartNoncashAcquisitionNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis_8a8e8b8e-7433-419f-89a7-d0ee87041a58" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_8a8e8b8e-7433-419f-89a7-d0ee87041a58_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_fe7e3eef-1b34-4993-88ed-06a4669a23d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncashOrPartNoncashAcquisitionNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis_8a8e8b8e-7433-419f-89a7-d0ee87041a58" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_fe7e3eef-1b34-4993-88ed-06a4669a23d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AcquisitionOfAdditionalInterestInExchangeForContributionOfPipelineAssetsMember_fe939fe4-8a9c-4aeb-9f4a-31252c25b177" xlink:href="pagp-20231231.xsd#pagp_AcquisitionOfAdditionalInterestInExchangeForContributionOfPipelineAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_fe7e3eef-1b34-4993-88ed-06a4669a23d4" xlink:to="loc_pagp_AcquisitionOfAdditionalInterestInExchangeForContributionOfPipelineAssetsMember_fe939fe4-8a9c-4aeb-9f4a-31252c25b177" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_8ea37c1b-94a0-4413-85b4-e7b4233a941e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_c9ea0c99-8532-46a0-bd58-9a5eb422d3b0" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_8ea37c1b-94a0-4413-85b4-e7b4233a941e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8ea37c1b-94a0-4413-85b4-e7b4233a941e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_8ea37c1b-94a0-4413-85b4-e7b4233a941e" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8ea37c1b-94a0-4413-85b4-e7b4233a941e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bc33794-4a80-4fe0-ab00-2100e25a795a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_8ea37c1b-94a0-4413-85b4-e7b4233a941e" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bc33794-4a80-4fe0-ab00-2100e25a795a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OMOGJVLLCMember_3e5b63e5-c04a-4d7b-b9bc-7ab25a46bac8" xlink:href="pagp-20231231.xsd#pagp_OMOGJVLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bc33794-4a80-4fe0-ab00-2100e25a795a" xlink:to="loc_pagp_OMOGJVLLCMember_3e5b63e5-c04a-4d7b-b9bc-7ab25a46bac8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AdvantagePipelineHoldingsLLCMember_ba28429a-3a3f-4763-8243-771efeac19e8" xlink:href="pagp-20231231.xsd#pagp_AdvantagePipelineHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bc33794-4a80-4fe0-ab00-2100e25a795a" xlink:to="loc_pagp_AdvantagePipelineHoldingsLLCMember_ba28429a-3a3f-4763-8243-771efeac19e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_c3c2c5b5-3746-4a3e-9417-cfea3a262854" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5bc33794-4a80-4fe0-ab00-2100e25a795a" xlink:to="loc_pagp_CactusIIPipelineLLCMember_c3c2c5b5-3746-4a3e-9417-cfea3a262854" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_1fe8309f-1bca-4c57-9fda-2e9fe54b0c87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_1fe8309f-1bca-4c57-9fda-2e9fe54b0c87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_7702ca1f-75ba-47db-a967-ba290ac53a47" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:to="loc_us-gaap_EquityMethodInvestments_7702ca1f-75ba-47db-a967-ba290ac53a47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_ff193539-8a27-4f93-92fe-77895c669e98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_ff193539-8a27-4f93-92fe-77895c669e98" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NumberOfPipelinesOrPartialPipelinesContributed_f177508c-773f-4521-b3ae-ebe12cd93d9f" xlink:href="pagp-20231231.xsd#pagp_NumberOfPipelinesOrPartialPipelinesContributed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:to="loc_pagp_NumberOfPipelinesOrPartialPipelinesContributed_f177508c-773f-4521-b3ae-ebe12cd93d9f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet_f1fdd6ed-f7e0-4b2f-9036-7545041a8061" xlink:href="pagp-20231231.xsd#pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:to="loc_pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet_f1fdd6ed-f7e0-4b2f-9036-7545041a8061" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CapitalContributionsToEquityMethodInvesteesExcludingCapitalizedInterest_d59ddc35-e403-4ee7-9264-dbc499292ee8" xlink:href="pagp-20231231.xsd#pagp_CapitalContributionsToEquityMethodInvesteesExcludingCapitalizedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:to="loc_pagp_CapitalContributionsToEquityMethodInvesteesExcludingCapitalizedInterest_d59ddc35-e403-4ee7-9264-dbc499292ee8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_29aa9c83-1c30-4181-8b64-daa33d21fd21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_e48d3496-7db9-4ada-a16a-aba2ff9d9378" xlink:to="loc_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_29aa9c83-1c30-4181-8b64-daa33d21fd21" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/InvestmentsinUnconsolidatedEntitiesSummarizedFinancialInformationDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#InvestmentsinUnconsolidatedEntitiesSummarizedFinancialInformationDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/InvestmentsinUnconsolidatedEntitiesSummarizedFinancialInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_0d4f0c97-39e6-4946-b546-4f5891bb6033" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_0d4f0c97-39e6-4946-b546-4f5891bb6033" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis_6c478740-2b6c-4357-979c-1db173dbc7d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_0d4f0c97-39e6-4946-b546-4f5891bb6033" xlink:to="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis_6c478740-2b6c-4357-979c-1db173dbc7d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_6c478740-2b6c-4357-979c-1db173dbc7d4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis_6c478740-2b6c-4357-979c-1db173dbc7d4" xlink:to="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_6c478740-2b6c-4357-979c-1db173dbc7d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_6ada3ba6-aadb-4666-ad29-363721d9e442" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis_6c478740-2b6c-4357-979c-1db173dbc7d4" xlink:to="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_6ada3ba6-aadb-4666-ad29-363721d9e442" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember_a4d30f60-e47e-4cbc-8864-7ec036adbf00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_6ada3ba6-aadb-4666-ad29-363721d9e442" xlink:to="loc_us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember_a4d30f60-e47e-4cbc-8864-7ec036adbf00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_e477294e-5281-49eb-8d8a-3487fd0398cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:to="loc_us-gaap_AssetsCurrent_e477294e-5281-49eb-8d8a-3487fd0398cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsNoncurrent_1251af6f-1da5-4dd5-b5ad-5f3f3615b87d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:to="loc_us-gaap_AssetsNoncurrent_1251af6f-1da5-4dd5-b5ad-5f3f3615b87d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_bf0726ef-4faf-458c-a7d2-52fd7659ba0c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:to="loc_us-gaap_LiabilitiesCurrent_bf0726ef-4faf-458c-a7d2-52fd7659ba0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesNoncurrent_63fdf27e-9d25-4738-a685-4c74aa259e94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:to="loc_us-gaap_LiabilitiesNoncurrent_63fdf27e-9d25-4738-a685-4c74aa259e94" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_ecfa439c-b23d-4ff1-9892-8d5d37535776" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:to="loc_us-gaap_Revenues_ecfa439c-b23d-4ff1-9892-8d5d37535776" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_83f3d7e4-d19f-45e0-809c-67012a242c55" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:to="loc_us-gaap_OperatingIncomeLoss_83f3d7e4-d19f-45e0-809c-67012a242c55" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_8c5f5e8e-7256-4750-b0eb-60bb0f3d0e6c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_b63e8e9d-2018-482e-a1ff-c6c57d7b6329" xlink:to="loc_us-gaap_GrossProfit_8c5f5e8e-7256-4750-b0eb-60bb0f3d0e6c" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/IntangibleAssetNetScheduleofIntangibleAssetsDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#IntangibleAssetNetScheduleofIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/IntangibleAssetNetScheduleofIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fd6e13d2-5724-46a4-bef4-3248eb5c67a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_1af69c56-2f11-406f-9128-ff3e1cde9b41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fd6e13d2-5724-46a4-bef4-3248eb5c67a9" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_1af69c56-2f11-406f-9128-ff3e1cde9b41" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_a836c963-7dfb-47f9-8459-79d1381193b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_1af69c56-2f11-406f-9128-ff3e1cde9b41" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_a836c963-7dfb-47f9-8459-79d1381193b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a836c963-7dfb-47f9-8459-79d1381193b1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_a836c963-7dfb-47f9-8459-79d1381193b1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a836c963-7dfb-47f9-8459-79d1381193b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_18040574-bb62-4d01-ac02-54aaf901eb60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_a836c963-7dfb-47f9-8459-79d1381193b1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_18040574-bb62-4d01-ac02-54aaf901eb60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_b35f99e6-0511-4130-9014-5f4c5d792843" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_18040574-bb62-4d01-ac02-54aaf901eb60" xlink:to="loc_us-gaap_CustomerRelationshipsMember_b35f99e6-0511-4130-9014-5f4c5d792843" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_a7e8adba-54a7-4d80-9c59-4396a8c34b3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_18040574-bb62-4d01-ac02-54aaf901eb60" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_a7e8adba-54a7-4d80-9c59-4396a8c34b3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_c3dfdfb8-40ea-4f00-b20f-e52cfc291603" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_1af69c56-2f11-406f-9128-ff3e1cde9b41" xlink:to="loc_srt_RangeAxis_c3dfdfb8-40ea-4f00-b20f-e52cfc291603" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c3dfdfb8-40ea-4f00-b20f-e52cfc291603_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_c3dfdfb8-40ea-4f00-b20f-e52cfc291603" xlink:to="loc_srt_RangeMember_c3dfdfb8-40ea-4f00-b20f-e52cfc291603_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a82beb9a-c91e-4013-85e5-40634d8fd9f3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_c3dfdfb8-40ea-4f00-b20f-e52cfc291603" xlink:to="loc_srt_RangeMember_a82beb9a-c91e-4013-85e5-40634d8fd9f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a61f33e2-18fe-4b13-ad6d-47fba1111df1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a82beb9a-c91e-4013-85e5-40634d8fd9f3" xlink:to="loc_srt_MinimumMember_a61f33e2-18fe-4b13-ad6d-47fba1111df1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_17717180-e019-460c-81ae-6d13a0464350" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a82beb9a-c91e-4013-85e5-40634d8fd9f3" xlink:to="loc_srt_MaximumMember_17717180-e019-460c-81ae-6d13a0464350" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_439f9236-4230-4747-8630-3b9fbd402ec2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fd6e13d2-5724-46a4-bef4-3248eb5c67a9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_439f9236-4230-4747-8630-3b9fbd402ec2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_cead4029-9739-4206-804c-495ab23939ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fd6e13d2-5724-46a4-bef4-3248eb5c67a9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_cead4029-9739-4206-804c-495ab23939ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_306830de-a238-4e36-a67f-b3648805eab1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fd6e13d2-5724-46a4-bef4-3248eb5c67a9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_306830de-a238-4e36-a67f-b3648805eab1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_60e65394-37ec-48e8-86c8-111bfa0abd1c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fd6e13d2-5724-46a4-bef4-3248eb5c67a9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_60e65394-37ec-48e8-86c8-111bfa0abd1c" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DebtScheduleofDebtDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DebtScheduleofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DebtScheduleofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_590ece3a-6212-4a35-9375-e4eca9051ed4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ScheduleOfDebtInstrumentsTable_9669b64a-0db0-492f-bc5c-5db63609b2df" xlink:href="pagp-20231231.xsd#pagp_ScheduleOfDebtInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_590ece3a-6212-4a35-9375-e4eca9051ed4" xlink:to="loc_pagp_ScheduleOfDebtInstrumentsTable_9669b64a-0db0-492f-bc5c-5db63609b2df" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_11f889dc-5208-4d0e-95bf-4fbc0e6c66bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ScheduleOfDebtInstrumentsTable_9669b64a-0db0-492f-bc5c-5db63609b2df" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_11f889dc-5208-4d0e-95bf-4fbc0e6c66bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_11f889dc-5208-4d0e-95bf-4fbc0e6c66bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_11f889dc-5208-4d0e-95bf-4fbc0e6c66bd" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_11f889dc-5208-4d0e-95bf-4fbc0e6c66bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_4b5a8948-528a-4317-b78f-a4e0663bfa60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_11f889dc-5208-4d0e-95bf-4fbc0e6c66bd" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_4b5a8948-528a-4317-b78f-a4e0663bfa60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_2c9eff6d-36dc-4957-87f0-5a026aabea4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_4b5a8948-528a-4317-b78f-a4e0663bfa60" xlink:to="loc_us-gaap_LineOfCreditMember_2c9eff6d-36dc-4957-87f0-5a026aabea4e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_c3387a56-ab42-4d67-84e7-9e869c37def2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_4b5a8948-528a-4317-b78f-a4e0663bfa60" xlink:to="loc_us-gaap_SeniorNotesMember_c3387a56-ab42-4d67-84e7-9e869c37def2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OtherDebtMember_bdac7821-d939-4015-aaa7-ba901712353e" xlink:href="pagp-20231231.xsd#pagp_OtherDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_4b5a8948-528a-4317-b78f-a4e0663bfa60" xlink:to="loc_pagp_OtherDebtMember_bdac7821-d939-4015-aaa7-ba901712353e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_c5cb6be6-b67a-4077-938b-dc56cfedd3c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ScheduleOfDebtInstrumentsTable_9669b64a-0db0-492f-bc5c-5db63609b2df" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_c5cb6be6-b67a-4077-938b-dc56cfedd3c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_c5cb6be6-b67a-4077-938b-dc56cfedd3c9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_c5cb6be6-b67a-4077-938b-dc56cfedd3c9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_c5cb6be6-b67a-4077-938b-dc56cfedd3c9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_439bcdf3-2a5a-41d2-8661-823cb0ac2b7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_c5cb6be6-b67a-4077-938b-dc56cfedd3c9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_439bcdf3-2a5a-41d2-8661-823cb0ac2b7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_cd2bae88-4e88-4161-a0e5-83ea789690b3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_439bcdf3-2a5a-41d2-8661-823cb0ac2b7e" xlink:to="loc_us-gaap_SeniorNotesMember_cd2bae88-4e88-4161-a0e5-83ea789690b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OtherLongTermDebtMember_84168d4a-d61f-4268-97ba-ad14fbf054ae" xlink:href="pagp-20231231.xsd#pagp_OtherLongTermDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_439bcdf3-2a5a-41d2-8661-823cb0ac2b7e" xlink:to="loc_pagp_OtherLongTermDebtMember_84168d4a-d61f-4268-97ba-ad14fbf054ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_af963d0d-03b5-488c-aec8-1cdad7fc4aea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ScheduleOfDebtInstrumentsTable_9669b64a-0db0-492f-bc5c-5db63609b2df" xlink:to="loc_us-gaap_DebtInstrumentAxis_af963d0d-03b5-488c-aec8-1cdad7fc4aea" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_af963d0d-03b5-488c-aec8-1cdad7fc4aea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_af963d0d-03b5-488c-aec8-1cdad7fc4aea" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_af963d0d-03b5-488c-aec8-1cdad7fc4aea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_af963d0d-03b5-488c-aec8-1cdad7fc4aea" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_bf82eb69-6d8e-44cc-9c29-d562a20e283e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_us-gaap_CommercialPaperMember_bf82eb69-6d8e-44cc-9c29-d562a20e283e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInJanuary2023At285PercentMember_03edfda7-d9dc-470e-8d77-cc832b36db28" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInJanuary2023At285PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInJanuary2023At285PercentMember_03edfda7-d9dc-470e-8d77-cc832b36db28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInOctober2023At385PercentMember_63332345-8b87-4246-a54f-3dc5da647034" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInOctober2023At385PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInOctober2023At385PercentMember_63332345-8b87-4246-a54f-3dc5da647034" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInNovember2024At360PercentMember_5d3d505a-2223-4a41-a4e5-c211486afc5b" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInNovember2024At360PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInNovember2024At360PercentMember_5d3d505a-2223-4a41-a4e5-c211486afc5b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInOctober2025At465PercentMember_fcbb8a74-fd19-4637-bfc0-abfe9ce47a83" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInOctober2025At465PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInOctober2025At465PercentMember_fcbb8a74-fd19-4637-bfc0-abfe9ce47a83" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueinDecember2026At4.50PercentMember_389c53f2-9738-44cb-8ac8-f8a69367f346" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueinDecember2026At4.50PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueinDecember2026At4.50PercentMember_389c53f2-9738-44cb-8ac8-f8a69367f346" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInDecember2029At355PercentMember_0296f1b5-4332-4648-b11d-f14c13657488" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInDecember2029At355PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInDecember2029At355PercentMember_0296f1b5-4332-4648-b11d-f14c13657488" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInSeptember2030At380PercentMember_5667de05-07fb-4c9c-85a4-e40ff81ca5a6" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInSeptember2030At380PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInSeptember2030At380PercentMember_5667de05-07fb-4c9c-85a4-e40ff81ca5a6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInMay2036At670PercentMember_c76da2fd-89b7-43d2-86fa-de102aa8c0bf" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInMay2036At670PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInMay2036At670PercentMember_c76da2fd-89b7-43d2-86fa-de102aa8c0bf" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInJanuary2037At665PercentMember_119f0d1e-3e25-470c-8681-1377847f8897" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInJanuary2037At665PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInJanuary2037At665PercentMember_119f0d1e-3e25-470c-8681-1377847f8897" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInJune2042At515PercentMember_706f9415-a509-47db-9ee2-dcce8b97f9a0" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInJune2042At515PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInJune2042At515PercentMember_706f9415-a509-47db-9ee2-dcce8b97f9a0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInJanuary2043At430PercentMember_5899d617-641d-4b0d-a146-f3e5609e5cf0" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInJanuary2043At430PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInJanuary2043At430PercentMember_5899d617-641d-4b0d-a146-f3e5609e5cf0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInJune2044At470PercentMember_6c2545ae-3ec3-4fa0-8fef-801086d4028f" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInJune2044At470PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInJune2044At470PercentMember_6c2545ae-3ec3-4fa0-8fef-801086d4028f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInFebruary2045At490PercentMember_9b8e1934-aed7-4b87-ae54-4a42b1b1f78e" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInFebruary2045At490PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4bc24a51-6ccd-4a95-8ef4-7ada9efc31bd" xlink:to="loc_pagp_SeniorNotesDueInFebruary2045At490PercentMember_9b8e1934-aed7-4b87-ae54-4a42b1b1f78e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4bbab46c-cec1-4f28-a128-836d88f2c259" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ScheduleOfDebtInstrumentsTable_9669b64a-0db0-492f-bc5c-5db63609b2df" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4bbab46c-cec1-4f28-a128-836d88f2c259" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_4bbab46c-cec1-4f28-a128-836d88f2c259_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4bbab46c-cec1-4f28-a128-836d88f2c259" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_4bbab46c-cec1-4f28-a128-836d88f2c259_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_10873967-7449-4770-a6c2-a5058ebb3c51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4bbab46c-cec1-4f28-a128-836d88f2c259" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_10873967-7449-4770-a6c2-a5058ebb3c51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_1ad35001-6903-4d0e-85a9-81013efee579" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_10873967-7449-4770-a6c2-a5058ebb3c51" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_1ad35001-6903-4d0e-85a9-81013efee579" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowingsAbstract_0be1cf2c-3c93-4706-aef0-776506494cd8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermBorrowingsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_590ece3a-6212-4a35-9375-e4eca9051ed4" xlink:to="loc_us-gaap_ShortTermBorrowingsAbstract_0be1cf2c-3c93-4706-aef0-776506494cd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_d057d3df-63e0-4ac7-88c7-5830cda9151e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermBorrowingsAbstract_0be1cf2c-3c93-4706-aef0-776506494cd8" xlink:to="loc_us-gaap_ShortTermBorrowings_d057d3df-63e0-4ac7-88c7-5830cda9151e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent_4904788d-9c1c-4f7d-9ff6-00da75b65b51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermBorrowingsAbstract_0be1cf2c-3c93-4706-aef0-776506494cd8" xlink:to="loc_us-gaap_DebtCurrent_4904788d-9c1c-4f7d-9ff6-00da75b65b51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_e906ab30-14e4-43d1-9a62-53e8c028cf0f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermBorrowingsAbstract_0be1cf2c-3c93-4706-aef0-776506494cd8" xlink:to="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_e906ab30-14e4-43d1-9a62-53e8c028cf0f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_f62ca28b-4f94-4bc2-892b-b4b8038e055d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermBorrowingsAbstract_0be1cf2c-3c93-4706-aef0-776506494cd8" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_f62ca28b-4f94-4bc2-892b-b4b8038e055d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAbstract_fd82b1d3-a078-4cdb-9868-84155b8796d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_590ece3a-6212-4a35-9375-e4eca9051ed4" xlink:to="loc_us-gaap_LongTermDebtAbstract_fd82b1d3-a078-4cdb-9868-84155b8796d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_c78c1dd6-da78-4d60-bd8d-0e4852b05c35" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_fd82b1d3-a078-4cdb-9868-84155b8796d8" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_c78c1dd6-da78-4d60-bd8d-0e4852b05c35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_4064be73-d155-4ae7-a6f7-e1f9e5e8ed42" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_fd82b1d3-a078-4cdb-9868-84155b8796d8" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_4064be73-d155-4ae7-a6f7-e1f9e5e8ed42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorLongTermNotes_3c7bb138-dd4f-4250-a0f0-f9607da7e7ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorLongTermNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_fd82b1d3-a078-4cdb-9868-84155b8796d8" xlink:to="loc_us-gaap_SeniorLongTermNotes_3c7bb138-dd4f-4250-a0f0-f9607da7e7ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLongTermDebtNoncurrent_b97c0283-ea23-4c04-bff7-4f9d43fbd482" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_fd82b1d3-a078-4cdb-9868-84155b8796d8" xlink:to="loc_us-gaap_OtherLongTermDebtNoncurrent_b97c0283-ea23-4c04-bff7-4f9d43fbd482" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_8b2f615b-7a73-483a-9f35-80fa8594c080" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_fd82b1d3-a078-4cdb-9868-84155b8796d8" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_8b2f615b-7a73-483a-9f35-80fa8594c080" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_83061e56-764d-41c9-8161-c304741e7541" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_fd82b1d3-a078-4cdb-9868-84155b8796d8" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_83061e56-764d-41c9-8161-c304741e7541" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_d12995c3-8969-47cb-a0f6-cf4258e60821" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_590ece3a-6212-4a35-9375-e4eca9051ed4" xlink:to="loc_us-gaap_DebtInstrumentTerm_d12995c3-8969-47cb-a0f6-cf4258e60821" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_915a7c0c-b1c1-4fd1-99e5-1ed4dcbe4ff5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_590ece3a-6212-4a35-9375-e4eca9051ed4" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_915a7c0c-b1c1-4fd1-99e5-1ed4dcbe4ff5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_b1450f64-7d2e-4744-b8fd-db02b28e784d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_590ece3a-6212-4a35-9375-e4eca9051ed4" xlink:to="loc_us-gaap_DebtInstrumentFairValue_b1450f64-7d2e-4744-b8fd-db02b28e784d" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DebtCommercialPaperandCreditFacilitiesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DebtCommercialPaperandCreditFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DebtCommercialPaperandCreditFacilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_02ac27ef-150e-4998-95ed-760dc0aa6c6c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_7f8369ab-0011-4684-aa57-5dd05208029d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_02ac27ef-150e-4998-95ed-760dc0aa6c6c" xlink:to="loc_us-gaap_DebtInstrumentTable_7f8369ab-0011-4684-aa57-5dd05208029d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_ac26191e-eb28-44d7-9298-acea6202b2df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7f8369ab-0011-4684-aa57-5dd05208029d" xlink:to="loc_us-gaap_CreditFacilityAxis_ac26191e-eb28-44d7-9298-acea6202b2df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_ac26191e-eb28-44d7-9298-acea6202b2df_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_ac26191e-eb28-44d7-9298-acea6202b2df" xlink:to="loc_us-gaap_CreditFacilityDomain_ac26191e-eb28-44d7-9298-acea6202b2df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_b541c97c-170c-4c74-9cd2-47607365abf8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_ac26191e-eb28-44d7-9298-acea6202b2df" xlink:to="loc_us-gaap_CreditFacilityDomain_b541c97c-170c-4c74-9cd2-47607365abf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_171fda4a-8951-4f42-91ab-77567e63a691" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b541c97c-170c-4c74-9cd2-47607365abf8" xlink:to="loc_us-gaap_CommercialPaperMember_171fda4a-8951-4f42-91ab-77567e63a691" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorSecuredHedgedInventoryFacilityMember_09090691-c83c-4cf0-ae85-351c891c37b5" xlink:href="pagp-20231231.xsd#pagp_SeniorSecuredHedgedInventoryFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b541c97c-170c-4c74-9cd2-47607365abf8" xlink:to="loc_pagp_SeniorSecuredHedgedInventoryFacilityMember_09090691-c83c-4cf0-ae85-351c891c37b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorUnsecuredRevolvingCreditFacilityMember_d8d3b833-9c36-490d-b3ee-2fcfec6625ba" xlink:href="pagp-20231231.xsd#pagp_SeniorUnsecuredRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b541c97c-170c-4c74-9cd2-47607365abf8" xlink:to="loc_pagp_SeniorUnsecuredRevolvingCreditFacilityMember_d8d3b833-9c36-490d-b3ee-2fcfec6625ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorUnsecuredRevolvingCreditFacilityMaturitingInAugust2027Member_28eb10cf-5c69-4227-99a5-c64d170f25da" xlink:href="pagp-20231231.xsd#pagp_SeniorUnsecuredRevolvingCreditFacilityMaturitingInAugust2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_SeniorUnsecuredRevolvingCreditFacilityMember_d8d3b833-9c36-490d-b3ee-2fcfec6625ba" xlink:to="loc_pagp_SeniorUnsecuredRevolvingCreditFacilityMaturitingInAugust2027Member_28eb10cf-5c69-4227-99a5-c64d170f25da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_9dde36d5-c219-4373-a5a4-ef1708d0eb52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7f8369ab-0011-4684-aa57-5dd05208029d" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_9dde36d5-c219-4373-a5a4-ef1708d0eb52" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_9dde36d5-c219-4373-a5a4-ef1708d0eb52_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_9dde36d5-c219-4373-a5a4-ef1708d0eb52" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_9dde36d5-c219-4373-a5a4-ef1708d0eb52_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_aeecf263-2d57-4498-9e5c-5cd703f5499e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_9dde36d5-c219-4373-a5a4-ef1708d0eb52" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_aeecf263-2d57-4498-9e5c-5cd703f5499e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandbyLettersOfCreditMember_95a73d15-3367-4ebf-a5df-506ceeb14ffd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StandbyLettersOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_aeecf263-2d57-4498-9e5c-5cd703f5499e" xlink:to="loc_us-gaap_StandbyLettersOfCreditMember_95a73d15-3367-4ebf-a5df-506ceeb14ffd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_42369bdf-e195-4c20-a0ba-bab1852b030a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7f8369ab-0011-4684-aa57-5dd05208029d" xlink:to="loc_srt_RangeAxis_42369bdf-e195-4c20-a0ba-bab1852b030a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_42369bdf-e195-4c20-a0ba-bab1852b030a_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_42369bdf-e195-4c20-a0ba-bab1852b030a" xlink:to="loc_srt_RangeMember_42369bdf-e195-4c20-a0ba-bab1852b030a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e3a6ec2e-9973-48da-95ac-75be8c92e22c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_42369bdf-e195-4c20-a0ba-bab1852b030a" xlink:to="loc_srt_RangeMember_e3a6ec2e-9973-48da-95ac-75be8c92e22c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_6921ba16-74f9-4f98-a2b6-8f91bc2bd805" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e3a6ec2e-9973-48da-95ac-75be8c92e22c" xlink:to="loc_srt_MinimumMember_6921ba16-74f9-4f98-a2b6-8f91bc2bd805" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_d7632e5c-6bab-418e-8eb8-36a25eca3419" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7f8369ab-0011-4684-aa57-5dd05208029d" xlink:to="loc_us-gaap_DebtInstrumentAxis_d7632e5c-6bab-418e-8eb8-36a25eca3419" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_d7632e5c-6bab-418e-8eb8-36a25eca3419_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_d7632e5c-6bab-418e-8eb8-36a25eca3419" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_d7632e5c-6bab-418e-8eb8-36a25eca3419_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_79809e9d-80e4-4711-9f15-50c6c606283c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_d7632e5c-6bab-418e-8eb8-36a25eca3419" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_79809e9d-80e4-4711-9f15-50c6c606283c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GOZoneTermLoanMember_04fe1fab-a763-483e-964c-8ec0a78d54b2" xlink:href="pagp-20231231.xsd#pagp_GOZoneTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_79809e9d-80e4-4711-9f15-50c6c606283c" xlink:to="loc_pagp_GOZoneTermLoanMember_04fe1fab-a763-483e-964c-8ec0a78d54b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_739f556b-4c5d-45c1-881e-587635a100e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_7f8369ab-0011-4684-aa57-5dd05208029d" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_739f556b-4c5d-45c1-881e-587635a100e6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_739f556b-4c5d-45c1-881e-587635a100e6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_739f556b-4c5d-45c1-881e-587635a100e6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_739f556b-4c5d-45c1-881e-587635a100e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_2581df02-5ab9-4b4c-baa2-4f7334d59b16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_739f556b-4c5d-45c1-881e-587635a100e6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_2581df02-5ab9-4b4c-baa2-4f7334d59b16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_TermLoanMember_d5886f89-5c82-4bba-bc8d-f87c3c31ef8c" xlink:href="pagp-20231231.xsd#pagp_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_2581df02-5ab9-4b4c-baa2-4f7334d59b16" xlink:to="loc_pagp_TermLoanMember_d5886f89-5c82-4bba-bc8d-f87c3c31ef8c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9a691b6a-2447-4574-8004-738c2f71cbfc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_02ac27ef-150e-4998-95ed-760dc0aa6c6c" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9a691b6a-2447-4574-8004-738c2f71cbfc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_36806d93-3fc5-45f3-83ad-95b7c2d4661c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_02ac27ef-150e-4998-95ed-760dc0aa6c6c" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_36806d93-3fc5-45f3-83ad-95b7c2d4661c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NumberOfOneYearExtensionsProvidedForUnderAgreement_28219483-223e-470d-83ae-ed710eecc7dd" xlink:href="pagp-20231231.xsd#pagp_NumberOfOneYearExtensionsProvidedForUnderAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_02ac27ef-150e-4998-95ed-760dc0aa6c6c" xlink:to="loc_pagp_NumberOfOneYearExtensionsProvidedForUnderAgreement_28219483-223e-470d-83ae-ed710eecc7dd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LineOfCreditFacilityPeriodForWhichTermOfCreditFacilityMayBeExtended_87b5fbe2-0686-4311-a6a9-623ab43b54ad" xlink:href="pagp-20231231.xsd#pagp_LineOfCreditFacilityPeriodForWhichTermOfCreditFacilityMayBeExtended"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_02ac27ef-150e-4998-95ed-760dc0aa6c6c" xlink:to="loc_pagp_LineOfCreditFacilityPeriodForWhichTermOfCreditFacilityMayBeExtended_87b5fbe2-0686-4311-a6a9-623ab43b54ad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSecuredDebt_b8184194-9991-4345-928c-4766a21f74ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfSecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_02ac27ef-150e-4998-95ed-760dc0aa6c6c" xlink:to="loc_us-gaap_RepaymentsOfSecuredDebt_b8184194-9991-4345-928c-4766a21f74ef" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DebtSeniorNotesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DebtSeniorNotesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DebtSeniorNotesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_fc8e1d4b-8ce8-446f-bdc9-b958380d7d20" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ScheduleOfDebtInstrumentsTable_22af3f1f-08fe-42bf-a3ff-2f9b0c7013fb" xlink:href="pagp-20231231.xsd#pagp_ScheduleOfDebtInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc8e1d4b-8ce8-446f-bdc9-b958380d7d20" xlink:to="loc_pagp_ScheduleOfDebtInstrumentsTable_22af3f1f-08fe-42bf-a3ff-2f9b0c7013fb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_407e8ef2-b121-4212-bbe8-bd35701f1dd1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ScheduleOfDebtInstrumentsTable_22af3f1f-08fe-42bf-a3ff-2f9b0c7013fb" xlink:to="loc_srt_OwnershipAxis_407e8ef2-b121-4212-bbe8-bd35701f1dd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_407e8ef2-b121-4212-bbe8-bd35701f1dd1_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_407e8ef2-b121-4212-bbe8-bd35701f1dd1" xlink:to="loc_srt_OwnershipDomain_407e8ef2-b121-4212-bbe8-bd35701f1dd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_8005339a-ebd3-4283-8b99-89b975b60689" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_407e8ef2-b121-4212-bbe8-bd35701f1dd1" xlink:to="loc_srt_OwnershipDomain_8005339a-ebd3-4283-8b99-89b975b60689" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ConsolidatedFinanceSubsidiaryIssuerMember_2d2a4601-ea5b-445d-ad8e-6c88295be722" xlink:href="pagp-20231231.xsd#pagp_ConsolidatedFinanceSubsidiaryIssuerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_8005339a-ebd3-4283-8b99-89b975b60689" xlink:to="loc_pagp_ConsolidatedFinanceSubsidiaryIssuerMember_2d2a4601-ea5b-445d-ad8e-6c88295be722" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_a1e1d6fe-99a4-475f-8b3e-1e233c7af908" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ScheduleOfDebtInstrumentsTable_22af3f1f-08fe-42bf-a3ff-2f9b0c7013fb" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_a1e1d6fe-99a4-475f-8b3e-1e233c7af908" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_a1e1d6fe-99a4-475f-8b3e-1e233c7af908_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a1e1d6fe-99a4-475f-8b3e-1e233c7af908" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_a1e1d6fe-99a4-475f-8b3e-1e233c7af908_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_f32c907e-3276-4520-a44b-315e53198537" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a1e1d6fe-99a4-475f-8b3e-1e233c7af908" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_f32c907e-3276-4520-a44b-315e53198537" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_d1776c1c-8934-4ffa-8878-fbce2ce893d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_f32c907e-3276-4520-a44b-315e53198537" xlink:to="loc_us-gaap_SeniorNotesMember_d1776c1c-8934-4ffa-8878-fbce2ce893d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_757dbce8-0998-4f69-a479-ebcda95d5aee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_ScheduleOfDebtInstrumentsTable_22af3f1f-08fe-42bf-a3ff-2f9b0c7013fb" xlink:to="loc_us-gaap_DebtInstrumentAxis_757dbce8-0998-4f69-a479-ebcda95d5aee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_757dbce8-0998-4f69-a479-ebcda95d5aee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_757dbce8-0998-4f69-a479-ebcda95d5aee" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_757dbce8-0998-4f69-a479-ebcda95d5aee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_f8e89919-6d42-40f3-b35c-e0272e9a9fa4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_757dbce8-0998-4f69-a479-ebcda95d5aee" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_f8e89919-6d42-40f3-b35c-e0272e9a9fa4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInOctober2023At385PercentMember_abd166b9-e568-40be-9a37-8062ca4d337d" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInOctober2023At385PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f8e89919-6d42-40f3-b35c-e0272e9a9fa4" xlink:to="loc_pagp_SeniorNotesDueInOctober2023At385PercentMember_abd166b9-e568-40be-9a37-8062ca4d337d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInJanuary2023At285PercentMember_dca6437f-073b-4293-9268-cd0e38a1fab4" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInJanuary2023At285PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f8e89919-6d42-40f3-b35c-e0272e9a9fa4" xlink:to="loc_pagp_SeniorNotesDueInJanuary2023At285PercentMember_dca6437f-073b-4293-9268-cd0e38a1fab4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeniorNotesDueInJune2022At365PercentMember_be4a03e0-43d3-4c19-ba49-1fb834dc9570" xlink:href="pagp-20231231.xsd#pagp_SeniorNotesDueInJune2022At365PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f8e89919-6d42-40f3-b35c-e0272e9a9fa4" xlink:to="loc_pagp_SeniorNotesDueInJune2022At365PercentMember_be4a03e0-43d3-4c19-ba49-1fb834dc9570" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_525c8a7f-7105-48d3-8e7a-e8148e9e461e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc8e1d4b-8ce8-446f-bdc9-b958380d7d20" xlink:to="loc_us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest_525c8a7f-7105-48d3-8e7a-e8148e9e461e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSeniorDebt_b6d2a3e4-6b46-471e-b5cb-ac3f57821575" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc8e1d4b-8ce8-446f-bdc9-b958380d7d20" xlink:to="loc_us-gaap_RepaymentsOfSeniorDebt_b6d2a3e4-6b46-471e-b5cb-ac3f57821575" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_32bceaaa-f82b-4e11-809c-1be7a637ffee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fc8e1d4b-8ce8-446f-bdc9-b958380d7d20" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_32bceaaa-f82b-4e11-809c-1be7a637ffee" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DebtDebtCovenantsDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DebtDebtCovenantsDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DebtDebtCovenantsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_32f50a14-f070-4f0a-aafb-0b5813b4027b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:to="loc_us-gaap_DebtInstrumentTable_32f50a14-f070-4f0a-aafb-0b5813b4027b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_5599a534-076a-44da-98f6-7f45ac099a67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_32f50a14-f070-4f0a-aafb-0b5813b4027b" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_5599a534-076a-44da-98f6-7f45ac099a67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_5599a534-076a-44da-98f6-7f45ac099a67_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_5599a534-076a-44da-98f6-7f45ac099a67" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_5599a534-076a-44da-98f6-7f45ac099a67_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_df46cba8-be05-4ff3-bfc3-bad210d96b59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_5599a534-076a-44da-98f6-7f45ac099a67" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_df46cba8-be05-4ff3-bfc3-bad210d96b59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandbyLettersOfCreditMember_a8d59e8a-0e80-40b3-91b5-089bb2b49ca3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StandbyLettersOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_df46cba8-be05-4ff3-bfc3-bad210d96b59" xlink:to="loc_us-gaap_StandbyLettersOfCreditMember_a8d59e8a-0e80-40b3-91b5-089bb2b49ca3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_f2c66593-d58e-4ad2-85cb-063989d80454" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_32f50a14-f070-4f0a-aafb-0b5813b4027b" xlink:to="loc_us-gaap_CreditFacilityAxis_f2c66593-d58e-4ad2-85cb-063989d80454" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_f2c66593-d58e-4ad2-85cb-063989d80454_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_f2c66593-d58e-4ad2-85cb-063989d80454" xlink:to="loc_us-gaap_CreditFacilityDomain_f2c66593-d58e-4ad2-85cb-063989d80454_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_d9354f29-a208-404f-950b-0b441373d4ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_f2c66593-d58e-4ad2-85cb-063989d80454" xlink:to="loc_us-gaap_CreditFacilityDomain_d9354f29-a208-404f-950b-0b441373d4ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LineOfCreditAndCommercialPaperMember_6dae8072-b131-47a2-ac43-7b431fb7869a" xlink:href="pagp-20231231.xsd#pagp_LineOfCreditAndCommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_d9354f29-a208-404f-950b-0b441373d4ee" xlink:to="loc_pagp_LineOfCreditAndCommercialPaperMember_6dae8072-b131-47a2-ac43-7b431fb7869a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_4b36a049-43eb-4c20-9b4d-5b08ec111bbb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_32f50a14-f070-4f0a-aafb-0b5813b4027b" xlink:to="loc_srt_RangeAxis_4b36a049-43eb-4c20-9b4d-5b08ec111bbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4b36a049-43eb-4c20-9b4d-5b08ec111bbb_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_4b36a049-43eb-4c20-9b4d-5b08ec111bbb" xlink:to="loc_srt_RangeMember_4b36a049-43eb-4c20-9b4d-5b08ec111bbb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a033b0cb-7195-460b-904c-6c31c157f0bb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_4b36a049-43eb-4c20-9b4d-5b08ec111bbb" xlink:to="loc_srt_RangeMember_a033b0cb-7195-460b-904c-6c31c157f0bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_358ea809-0b94-4f1d-9fbf-55b6af512336" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a033b0cb-7195-460b-904c-6c31c157f0bb" xlink:to="loc_srt_MaximumMember_358ea809-0b94-4f1d-9fbf-55b6af512336" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DebtInstrumentCoverageRatioDebtToEBITDAMaximum_53d04018-cc6f-4310-abf3-255b2071a33d" xlink:href="pagp-20231231.xsd#pagp_DebtInstrumentCoverageRatioDebtToEBITDAMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:to="loc_pagp_DebtInstrumentCoverageRatioDebtToEBITDAMaximum_53d04018-cc6f-4310-abf3-255b2071a33d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DebtInstrumentCoverageRatioDebtToEBITDAAcquisitionPeriodMaximum_8c43f975-48e7-49f1-b1e1-a48ac8187501" xlink:href="pagp-20231231.xsd#pagp_DebtInstrumentCoverageRatioDebtToEBITDAAcquisitionPeriodMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:to="loc_pagp_DebtInstrumentCoverageRatioDebtToEBITDAAcquisitionPeriodMaximum_8c43f975-48e7-49f1-b1e1-a48ac8187501" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AcquisitionMeasurementPeriodThreshold_d8034187-a9b3-4971-a0fa-40d6df4f599e" xlink:href="pagp-20231231.xsd#pagp_AcquisitionMeasurementPeriodThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:to="loc_pagp_AcquisitionMeasurementPeriodThreshold_d8034187-a9b3-4971-a0fa-40d6df4f599e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfDebt_81486f86-d5d3-4e63-b2f8-bf01af882d58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfDebt_81486f86-d5d3-4e63-b2f8-bf01af882d58" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_a890a0dd-7ed1-46ba-b1da-63c30d01e4f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:to="loc_us-gaap_RepaymentsOfDebt_a890a0dd-7ed1-46ba-b1da-63c30d01e4f6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_93d6c71a-e038-40ef-8204-c834a1f5900c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:to="loc_us-gaap_DebtInstrumentTerm_93d6c71a-e038-40ef-8204-c834a1f5900c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_b566baee-3560-487f-a706-ee486b7f4d16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f43e0e8e-0dfd-4f2e-83df-9f571f919824" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_b566baee-3560-487f-a706-ee486b7f4d16" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PartnersCapitalandDistributionsSharesandExchangeandRedemptionRightsDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#PartnersCapitalandDistributionsSharesandExchangeandRedemptionRightsDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PartnersCapitalandDistributionsSharesandExchangeandRedemptionRightsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionLineItems_1bbba0d0-1eba-4c1b-bfe9-187f9e50b20a" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionsTable_4876b1f9-bf5e-4d4d-9bf1-b4c146a45e8d" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_1bbba0d0-1eba-4c1b-bfe9-187f9e50b20a" xlink:to="loc_pagp_PartnersCapitalAndDistributionsTable_4876b1f9-bf5e-4d4d-9bf1-b4c146a45e8d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_09599dd6-3360-458e-b169-fdad4bba87d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_4876b1f9-bf5e-4d4d-9bf1-b4c146a45e8d" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_09599dd6-3360-458e-b169-fdad4bba87d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_09599dd6-3360-458e-b169-fdad4bba87d7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_09599dd6-3360-458e-b169-fdad4bba87d7" xlink:to="loc_us-gaap_RelatedPartyDomain_09599dd6-3360-458e-b169-fdad4bba87d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_37dd17f9-52ad-427d-8ec0-6ca80d588fef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_09599dd6-3360-458e-b169-fdad4bba87d7" xlink:to="loc_us-gaap_RelatedPartyDomain_37dd17f9-52ad-427d-8ec0-6ca80d588fef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_9e029494-662d-4ecf-9f2f-c4436c0d55b6" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_37dd17f9-52ad-427d-8ec0-6ca80d588fef" xlink:to="loc_pagp_PlainsAAPLPMember_9e029494-662d-4ecf-9f2f-c4436c0d55b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockByUniqueDescriptionAxis_2a99f751-8066-4e48-a49c-87c7eae75ad3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockByUniqueDescriptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_4876b1f9-bf5e-4d4d-9bf1-b4c146a45e8d" xlink:to="loc_us-gaap_ConversionOfStockByUniqueDescriptionAxis_2a99f751-8066-4e48-a49c-87c7eae75ad3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockNameDomain_2a99f751-8066-4e48-a49c-87c7eae75ad3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConversionOfStockByUniqueDescriptionAxis_2a99f751-8066-4e48-a49c-87c7eae75ad3" xlink:to="loc_us-gaap_ConversionOfStockNameDomain_2a99f751-8066-4e48-a49c-87c7eae75ad3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockNameDomain_fd4aa7d5-eda8-43a9-ab4a-05b42eb35649" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConversionOfStockByUniqueDescriptionAxis_2a99f751-8066-4e48-a49c-87c7eae75ad3" xlink:to="loc_us-gaap_ConversionOfStockNameDomain_fd4aa7d5-eda8-43a9-ab4a-05b42eb35649" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ExchangeOfAAPUnitsAndClassBSharesForClassASharesMember_29d914b1-2de3-40ea-be69-904cbda8ef32" xlink:href="pagp-20231231.xsd#pagp_ExchangeOfAAPUnitsAndClassBSharesForClassASharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockNameDomain_fd4aa7d5-eda8-43a9-ab4a-05b42eb35649" xlink:to="loc_pagp_ExchangeOfAAPUnitsAndClassBSharesForClassASharesMember_29d914b1-2de3-40ea-be69-904cbda8ef32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_5976b52f-9e8b-4e19-913a-41aae6d0c19a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_4876b1f9-bf5e-4d4d-9bf1-b4c146a45e8d" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_5976b52f-9e8b-4e19-913a-41aae6d0c19a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_5976b52f-9e8b-4e19-913a-41aae6d0c19a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_5976b52f-9e8b-4e19-913a-41aae6d0c19a" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_5976b52f-9e8b-4e19-913a-41aae6d0c19a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_bbe99582-a0f0-4b67-9e89-3a35f820fd95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_5976b52f-9e8b-4e19-913a-41aae6d0c19a" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_bbe99582-a0f0-4b67-9e89-3a35f820fd95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_51043c3f-acb5-40b6-949e-029625fd7b52" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_bbe99582-a0f0-4b67-9e89-3a35f820fd95" xlink:to="loc_pagp_SharesClassAMember_51043c3f-acb5-40b6-949e-029625fd7b52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassBMember_516b5805-08db-4ed2-9436-00581eb32e2b" xlink:href="pagp-20231231.xsd#pagp_SharesClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_bbe99582-a0f0-4b67-9e89-3a35f820fd95" xlink:to="loc_pagp_SharesClassBMember_516b5805-08db-4ed2-9436-00581eb32e2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassCMember_ddf76a4d-2e17-4c2c-91a1-889f1afebeb0" xlink:href="pagp-20231231.xsd#pagp_SharesClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_bbe99582-a0f0-4b67-9e89-3a35f820fd95" xlink:to="loc_pagp_SharesClassCMember_ddf76a4d-2e17-4c2c-91a1-889f1afebeb0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_UnitConversionRatio_eb8130ae-dee2-429c-b1f2-9071aad1abb1" xlink:href="pagp-20231231.xsd#pagp_UnitConversionRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_1bbba0d0-1eba-4c1b-bfe9-187f9e50b20a" xlink:to="loc_pagp_UnitConversionRatio_eb8130ae-dee2-429c-b1f2-9071aad1abb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_721073de-afbf-49dd-96b6-6f0dd47ae746" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInPartnersCapitalRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_1bbba0d0-1eba-4c1b-bfe9-187f9e50b20a" xlink:to="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_721073de-afbf-49dd-96b6-6f0dd47ae746" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding_2d618332-b369-4e40-a101-476f66680739" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_721073de-afbf-49dd-96b6-6f0dd47ae746" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding_2d618332-b369-4e40-a101-476f66680739" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LimitedPartnersCapitalAccountSharesIssuedFromConversion_8b4bf4ee-0378-4cf1-9c29-3922415633fe" xlink:href="pagp-20231231.xsd#pagp_LimitedPartnersCapitalAccountSharesIssuedFromConversion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_721073de-afbf-49dd-96b6-6f0dd47ae746" xlink:to="loc_pagp_LimitedPartnersCapitalAccountSharesIssuedFromConversion_8b4bf4ee-0378-4cf1-9c29-3922415633fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LimitedPartnersCapitalAccountSharesIssuedExchangedinExchangeRightExercises_26b4f391-8eee-4fd7-9f1d-d9d24f52e497" xlink:href="pagp-20231231.xsd#pagp_LimitedPartnersCapitalAccountSharesIssuedExchangedinExchangeRightExercises"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_721073de-afbf-49dd-96b6-6f0dd47ae746" xlink:to="loc_pagp_LimitedPartnersCapitalAccountSharesIssuedExchangedinExchangeRightExercises_26b4f391-8eee-4fd7-9f1d-d9d24f52e497" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LimitedPartnersCapitalAccountSharesIssuedRedeemedinRedemptionRightExercises_8c739ce2-41b1-4a5f-8340-b5ed2d3cb008" xlink:href="pagp-20231231.xsd#pagp_LimitedPartnersCapitalAccountSharesIssuedRedeemedinRedemptionRightExercises"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_721073de-afbf-49dd-96b6-6f0dd47ae746" xlink:to="loc_pagp_LimitedPartnersCapitalAccountSharesIssuedRedeemedinRedemptionRightExercises_8c739ce2-41b1-4a5f-8340-b5ed2d3cb008" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAccountSharesCancellationOfShares_5229aa78-8db3-427f-8c30-7461813dfbb6" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAccountSharesCancellationOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_721073de-afbf-49dd-96b6-6f0dd47ae746" xlink:to="loc_pagp_PartnersCapitalAccountSharesCancellationOfShares_5229aa78-8db3-427f-8c30-7461813dfbb6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalUnitsOther_15727ee5-ff21-4c34-a7e0-2239cb485977" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalUnitsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInPartnersCapitalRollForward_721073de-afbf-49dd-96b6-6f0dd47ae746" xlink:to="loc_pagp_PartnersCapitalUnitsOther_15727ee5-ff21-4c34-a7e0-2239cb485977" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding_8e130695-44f2-4652-9029-7b185e0dab87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PartnersCapitalandDistributionsDistributionsClassADetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#PartnersCapitalandDistributionsDistributionsClassADetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PartnersCapitalandDistributionsDistributionsClassADetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionLineItems_2023d96f-3742-407b-8e5e-911710ab2d61" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionsTable_caf2f54f-5b93-45b2-a8d7-2f38ee73c3c6" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_2023d96f-3742-407b-8e5e-911710ab2d61" xlink:to="loc_pagp_PartnersCapitalAndDistributionsTable_caf2f54f-5b93-45b2-a8d7-2f38ee73c3c6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_26f95fd6-6110-49a0-9bd0-8ef2886b285a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_caf2f54f-5b93-45b2-a8d7-2f38ee73c3c6" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_26f95fd6-6110-49a0-9bd0-8ef2886b285a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_26f95fd6-6110-49a0-9bd0-8ef2886b285a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_26f95fd6-6110-49a0-9bd0-8ef2886b285a" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_26f95fd6-6110-49a0-9bd0-8ef2886b285a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_a2e91508-8fbe-4f09-9847-acdbab47302c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_26f95fd6-6110-49a0-9bd0-8ef2886b285a" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_a2e91508-8fbe-4f09-9847-acdbab47302c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassAMember_33f631c4-48a4-495b-b0b6-82cf922a6f60" xlink:href="pagp-20231231.xsd#pagp_SharesClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_a2e91508-8fbe-4f09-9847-acdbab47302c" xlink:to="loc_pagp_SharesClassAMember_33f631c4-48a4-495b-b0b6-82cf922a6f60" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_7d02e385-bcc5-4316-a3dc-1ccfd2cd2b82" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_caf2f54f-5b93-45b2-a8d7-2f38ee73c3c6" xlink:to="loc_us-gaap_DividendsAxis_7d02e385-bcc5-4316-a3dc-1ccfd2cd2b82" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_7d02e385-bcc5-4316-a3dc-1ccfd2cd2b82_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_7d02e385-bcc5-4316-a3dc-1ccfd2cd2b82" xlink:to="loc_us-gaap_DividendsDomain_7d02e385-bcc5-4316-a3dc-1ccfd2cd2b82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_bf572813-2696-4548-8aa1-e933877a53ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_7d02e385-bcc5-4316-a3dc-1ccfd2cd2b82" xlink:to="loc_us-gaap_DividendsDomain_bf572813-2696-4548-8aa1-e933877a53ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_FourthQuarterDistributionMember_8400b09d-e501-43de-a704-8e273bce674a" xlink:href="pagp-20231231.xsd#pagp_FourthQuarterDistributionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsDomain_bf572813-2696-4548-8aa1-e933877a53ab" xlink:to="loc_pagp_FourthQuarterDistributionMember_8400b09d-e501-43de-a704-8e273bce674a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_c701bcde-fffb-481c-8385-e8b5f5d5172c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_caf2f54f-5b93-45b2-a8d7-2f38ee73c3c6" xlink:to="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_c701bcde-fffb-481c-8385-e8b5f5d5172c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionTypeDomain_c701bcde-fffb-481c-8385-e8b5f5d5172c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_c701bcde-fffb-481c-8385-e8b5f5d5172c" xlink:to="loc_us-gaap_DistributionTypeDomain_c701bcde-fffb-481c-8385-e8b5f5d5172c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionTypeDomain_36b6cbfa-ba68-4cd0-b27a-f757b9874c34" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_c701bcde-fffb-481c-8385-e8b5f5d5172c" xlink:to="loc_us-gaap_DistributionTypeDomain_36b6cbfa-ba68-4cd0-b27a-f757b9874c34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashDistributionMember_f599f067-9f1b-4605-8680-e41b68ef8c2c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashDistributionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DistributionTypeDomain_36b6cbfa-ba68-4cd0-b27a-f757b9874c34" xlink:to="loc_us-gaap_CashDistributionMember_f599f067-9f1b-4605-8680-e41b68ef8c2c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_ccc7456c-a745-4a22-863f-2fc0efbbe000" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_caf2f54f-5b93-45b2-a8d7-2f38ee73c3c6" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_ccc7456c-a745-4a22-863f-2fc0efbbe000" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_ccc7456c-a745-4a22-863f-2fc0efbbe000_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ccc7456c-a745-4a22-863f-2fc0efbbe000" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_ccc7456c-a745-4a22-863f-2fc0efbbe000_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_3145723c-5e6a-4c49-b461-b9af24e4cd02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ccc7456c-a745-4a22-863f-2fc0efbbe000" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_3145723c-5e6a-4c49-b461-b9af24e4cd02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_9e1759ab-cb5b-4fde-84c8-12122c7bad08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_3145723c-5e6a-4c49-b461-b9af24e4cd02" xlink:to="loc_us-gaap_SubsequentEventMember_9e1759ab-cb5b-4fde-84c8-12122c7bad08" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_071599ae-a451-433c-931a-684968a44adb" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_caf2f54f-5b93-45b2-a8d7-2f38ee73c3c6" xlink:to="loc_dei_LegalEntityAxis_071599ae-a451-433c-931a-684968a44adb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_071599ae-a451-433c-931a-684968a44adb_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_071599ae-a451-433c-931a-684968a44adb" xlink:to="loc_dei_EntityDomain_071599ae-a451-433c-931a-684968a44adb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_e2f47ea6-a715-4c54-8cf2-03a25d3f12f7" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_071599ae-a451-433c-931a-684968a44adb" xlink:to="loc_dei_EntityDomain_e2f47ea6-a715-4c54-8cf2-03a25d3f12f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_b36de920-108d-436a-be39-c029aaec9042" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_e2f47ea6-a715-4c54-8cf2-03a25d3f12f7" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_b36de920-108d-436a-be39-c029aaec9042" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PercentageDistributionOfAvailableCash_b7983714-c2e6-43ca-b61f-6cc33fbcbe74" xlink:href="pagp-20231231.xsd#pagp_PercentageDistributionOfAvailableCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_2023d96f-3742-407b-8e5e-911710ab2d61" xlink:to="loc_pagp_PercentageDistributionOfAvailableCash_b7983714-c2e6-43ca-b61f-6cc33fbcbe74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NumberOfDaysRequiredForDistributionToShareholdersAfterEndOfQuarter_7f2374f4-cb0f-4fe8-b45e-a4d07cda6110" xlink:href="pagp-20231231.xsd#pagp_NumberOfDaysRequiredForDistributionToShareholdersAfterEndOfQuarter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_2023d96f-3742-407b-8e5e-911710ab2d61" xlink:to="loc_pagp_NumberOfDaysRequiredForDistributionToShareholdersAfterEndOfQuarter_7f2374f4-cb0f-4fe8-b45e-a4d07cda6110" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountDistributionAmount_195b6bd6-0002-48cf-a6ab-028f1b8fa9db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountDistributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_2023d96f-3742-407b-8e5e-911710ab2d61" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountDistributionAmount_195b6bd6-0002-48cf-a6ab-028f1b8fa9db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit_6eb2a9cc-ca24-4977-9079-0752a57b6036" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_2023d96f-3742-407b-8e5e-911710ab2d61" xlink:to="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit_6eb2a9cc-ca24-4977-9079-0752a57b6036" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit_4a8a63f5-2e84-4857-934c-8beb1b634536" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_2023d96f-3742-407b-8e5e-911710ab2d61" xlink:to="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit_4a8a63f5-2e84-4857-934c-8beb1b634536" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PartnersCapitalandDistributionsConsolidatedSubsidiariesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#PartnersCapitalandDistributionsConsolidatedSubsidiariesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PartnersCapitalandDistributionsConsolidatedSubsidiariesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_95339eb5-147d-4391-8667-b8ed8ffc7bc1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_srt_OwnershipAxis_95339eb5-147d-4391-8667-b8ed8ffc7bc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_95339eb5-147d-4391-8667-b8ed8ffc7bc1_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_95339eb5-147d-4391-8667-b8ed8ffc7bc1" xlink:to="loc_srt_OwnershipDomain_95339eb5-147d-4391-8667-b8ed8ffc7bc1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_bd2fcecd-28c2-4d43-a250-6ab9c1c09a6c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_95339eb5-147d-4391-8667-b8ed8ffc7bc1" xlink:to="loc_srt_OwnershipDomain_bd2fcecd-28c2-4d43-a250-6ab9c1c09a6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_488d0f7d-eb3a-4b8d-8af9-2a92b67f0f28" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_bd2fcecd-28c2-4d43-a250-6ab9c1c09a6c" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_488d0f7d-eb3a-4b8d-8af9-2a92b67f0f28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_32a61f92-20f0-409d-8e6c-3e12e380790c" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_bd2fcecd-28c2-4d43-a250-6ab9c1c09a6c" xlink:to="loc_pagp_PlainsAAPLPMember_32a61f92-20f0-409d-8e6c-3e12e380790c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_a1801e3e-0541-47d8-8eaf-aff87e96f761" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_bd2fcecd-28c2-4d43-a250-6ab9c1c09a6c" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_a1801e3e-0541-47d8-8eaf-aff87e96f761" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_RedRiverPipelineCompanyLLCMember_b32ea321-93d1-4ddd-b22a-43036641416c" xlink:href="pagp-20231231.xsd#pagp_RedRiverPipelineCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_bd2fcecd-28c2-4d43-a250-6ab9c1c09a6c" xlink:to="loc_pagp_RedRiverPipelineCompanyLLCMember_b32ea321-93d1-4ddd-b22a-43036641416c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_4f21d1d2-4aa7-4b2e-9835-eedbe63ebc9b" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_bd2fcecd-28c2-4d43-a250-6ab9c1c09a6c" xlink:to="loc_pagp_CactusIIPipelineLLCMember_4f21d1d2-4aa7-4b2e-9835-eedbe63ebc9b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_cfd9f0fa-026d-4d0d-a635-f2baa34ad54c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_cfd9f0fa-026d-4d0d-a635-f2baa34ad54c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_cfd9f0fa-026d-4d0d-a635-f2baa34ad54c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_cfd9f0fa-026d-4d0d-a635-f2baa34ad54c" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_cfd9f0fa-026d-4d0d-a635-f2baa34ad54c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c7abefa1-a021-4342-a2a1-fa0ada21d773" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_cfd9f0fa-026d-4d0d-a635-f2baa34ad54c" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c7abefa1-a021-4342-a2a1-fa0ada21d773" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CommonUnitsAndSeriesAPreferredUnitsMember_960493ea-55e1-4e98-a4fd-ccfd4d6eb7fb" xlink:href="pagp-20231231.xsd#pagp_CommonUnitsAndSeriesAPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c7abefa1-a021-4342-a2a1-fa0ada21d773" xlink:to="loc_pagp_CommonUnitsAndSeriesAPreferredUnitsMember_960493ea-55e1-4e98-a4fd-ccfd4d6eb7fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeriesBPreferredUnitsMember_03a65e03-92e8-4e6c-aaa2-2aa02c6aec3a" xlink:href="pagp-20231231.xsd#pagp_SeriesBPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c7abefa1-a021-4342-a2a1-fa0ada21d773" xlink:to="loc_pagp_SeriesBPreferredUnitsMember_03a65e03-92e8-4e6c-aaa2-2aa02c6aec3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_35b7e5c4-0445-493a-99f1-655209af30b4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_srt_CounterpartyNameAxis_35b7e5c4-0445-493a-99f1-655209af30b4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_35b7e5c4-0445-493a-99f1-655209af30b4_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_35b7e5c4-0445-493a-99f1-655209af30b4" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_35b7e5c4-0445-493a-99f1-655209af30b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_569b200d-be29-4187-9309-1197537b79da" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_35b7e5c4-0445-493a-99f1-655209af30b4" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_569b200d-be29-4187-9309-1197537b79da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EnbridgeMember_8e093da7-f7a9-42a7-9bfd-d863f589f61e" xlink:href="pagp-20231231.xsd#pagp_EnbridgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_569b200d-be29-4187-9309-1197537b79da" xlink:to="loc_pagp_EnbridgeMember_8e093da7-f7a9-42a7-9bfd-d863f589f61e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OryxMidstreamHoldingsLLCMember_cb49b390-e82f-4a90-8f47-6255cfa1b8d0" xlink:href="pagp-20231231.xsd#pagp_OryxMidstreamHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_569b200d-be29-4187-9309-1197537b79da" xlink:to="loc_pagp_OryxMidstreamHoldingsLLCMember_cb49b390-e82f-4a90-8f47-6255cfa1b8d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_945c2d14-fae5-445b-96b2-c9a4f7cc8981" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_us-gaap_TransactionTypeAxis_945c2d14-fae5-445b-96b2-c9a4f7cc8981" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_945c2d14-fae5-445b-96b2-c9a4f7cc8981_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_945c2d14-fae5-445b-96b2-c9a4f7cc8981" xlink:to="loc_us-gaap_TransactionDomain_945c2d14-fae5-445b-96b2-c9a4f7cc8981_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_ebcc7659-0a90-482a-a980-ebaa957959ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_945c2d14-fae5-445b-96b2-c9a4f7cc8981" xlink:to="loc_us-gaap_TransactionDomain_ebcc7659-0a90-482a-a980-ebaa957959ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_JointVentureFormationMember_1e50eeb3-205d-466d-8c84-8005247a6974" xlink:href="pagp-20231231.xsd#pagp_JointVentureFormationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_ebcc7659-0a90-482a-a980-ebaa957959ab" xlink:to="loc_pagp_JointVentureFormationMember_1e50eeb3-205d-466d-8c84-8005247a6974" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_7541c120-ee34-4839-848c-dc18f1cd5b17" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_dei_LegalEntityAxis_7541c120-ee34-4839-848c-dc18f1cd5b17" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_7541c120-ee34-4839-848c-dc18f1cd5b17_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_7541c120-ee34-4839-848c-dc18f1cd5b17" xlink:to="loc_dei_EntityDomain_7541c120-ee34-4839-848c-dc18f1cd5b17_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_ff14f9f4-874a-49d5-a433-6ed77f63283e" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_7541c120-ee34-4839-848c-dc18f1cd5b17" xlink:to="loc_dei_EntityDomain_ff14f9f4-874a-49d5-a433-6ed77f63283e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_be574e0c-4214-4790-97d7-0552af1bc5a8" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_ff14f9f4-874a-49d5-a433-6ed77f63283e" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_be574e0c-4214-4790-97d7-0552af1bc5a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsAxis_e3073066-03da-4509-98f5-a22836b7d039" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_us-gaap_PartnerCapitalComponentsAxis_e3073066-03da-4509-98f5-a22836b7d039" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_e3073066-03da-4509-98f5-a22836b7d039_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_e3073066-03da-4509-98f5-a22836b7d039" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_e3073066-03da-4509-98f5-a22836b7d039_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_fc281d77-f48d-4307-a313-3e4c7d60d469" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_e3073066-03da-4509-98f5-a22836b7d039" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_fc281d77-f48d-4307-a313-3e4c7d60d469" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_991201e4-0e3e-436e-beae-72b1c71c7e61" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_fc281d77-f48d-4307-a313-3e4c7d60d469" xlink:to="loc_us-gaap_NoncontrollingInterestMember_991201e4-0e3e-436e-beae-72b1c71c7e61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_cface734-b67b-4bfe-ae25-54425d6499b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_fc281d77-f48d-4307-a313-3e4c7d60d469" xlink:to="loc_us-gaap_ParentMember_cface734-b67b-4bfe-ae25-54425d6499b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_b22fbf16-1b2b-4fba-98f0-35e064e7b211" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_b22fbf16-1b2b-4fba-98f0-35e064e7b211" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_b22fbf16-1b2b-4fba-98f0-35e064e7b211_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_b22fbf16-1b2b-4fba-98f0-35e064e7b211" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_b22fbf16-1b2b-4fba-98f0-35e064e7b211_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_f2c38e46-8fe9-4f72-8096-b18a6a5f20a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_b22fbf16-1b2b-4fba-98f0-35e064e7b211" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_f2c38e46-8fe9-4f72-8096-b18a6a5f20a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CommonEquityRepurchaseProgramMember_3b6e1722-4488-4f85-8ad6-781fb7de0683" xlink:href="pagp-20231231.xsd#pagp_CommonEquityRepurchaseProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_f2c38e46-8fe9-4f72-8096-b18a6a5f20a7" xlink:to="loc_pagp_CommonEquityRepurchaseProgramMember_3b6e1722-4488-4f85-8ad6-781fb7de0683" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_39aaf68f-568a-4fc6-8c2c-edb900b195ea" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_39aaf68f-568a-4fc6-8c2c-edb900b195ea" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_39aaf68f-568a-4fc6-8c2c-edb900b195ea_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_39aaf68f-568a-4fc6-8c2c-edb900b195ea" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_39aaf68f-568a-4fc6-8c2c-edb900b195ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_4d58e524-52c4-40d4-b9d0-8044fe8a721b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_39aaf68f-568a-4fc6-8c2c-edb900b195ea" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_4d58e524-52c4-40d4-b9d0-8044fe8a721b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_135170e8-8a5a-4ca9-8f39-41414d783494" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_4d58e524-52c4-40d4-b9d0-8044fe8a721b" xlink:to="loc_pagp_CactusIIPipelineLLCMember_135170e8-8a5a-4ca9-8f39-41414d783494" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_1c81ce1d-94b6-40c8-b0bb-0c779845daea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_fb92a8fd-9455-4402-b6e0-dd36c8a5e637" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_1c81ce1d-94b6-40c8-b0bb-0c779845daea" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1c81ce1d-94b6-40c8-b0bb-0c779845daea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_1c81ce1d-94b6-40c8-b0bb-0c779845daea" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1c81ce1d-94b6-40c8-b0bb-0c779845daea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d864dce6-f4c6-48e2-b3ce-add46f747d92" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_1c81ce1d-94b6-40c8-b0bb-0c779845daea" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d864dce6-f4c6-48e2-b3ce-add46f747d92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_f36c4799-d34b-42d2-9a89-650c0563d2ff" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d864dce6-f4c6-48e2-b3ce-add46f747d92" xlink:to="loc_pagp_CactusIIPipelineLLCMember_f36c4799-d34b-42d2-9a89-650c0563d2ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_31541e83-2001-4ef7-a481-d73fef9e714f" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d864dce6-f4c6-48e2-b3ce-add46f747d92" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_31541e83-2001-4ef7-a481-d73fef9e714f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_9e357f06-9886-4b4c-89ef-7b88b9f12753" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_9e357f06-9886-4b4c-89ef-7b88b9f12753" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_e512b8d3-fcfd-4163-a689-8051adcd0f96" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_e512b8d3-fcfd-4163-a689-8051adcd0f96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage_52b606f6-2a52-41c3-b8bc-17ade28ffb50" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage_52b606f6-2a52-41c3-b8bc-17ade28ffb50" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_59f402da-877c-4278-83f6-8bed96274619" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_59f402da-877c-4278-83f6-8bed96274619" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_92e11f9f-4b69-4558-b1a5-52671acf0b86" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_92e11f9f-4b69-4558-b1a5-52671acf0b86" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountAcquisitions_fc32f7a9-d60c-45b2-a5dc-4b904a9514ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_PartnersCapitalAccountAcquisitions_fc32f7a9-d60c-45b2-a5dc-4b904a9514ae" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_93f2b1a6-6a7c-4148-b8fe-18aa5bb14f72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_93f2b1a6-6a7c-4148-b8fe-18aa5bb14f72" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_81c1be7c-c530-4343-b0c1-82b81ca0b8d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_81c1be7c-c530-4343-b0c1-82b81ca0b8d9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_2854f6c9-a170-477b-a2e2-bf2afe08aa83" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_5d77dd54-9e80-49b8-8d75-faf7c56d2f4a" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_2854f6c9-a170-477b-a2e2-bf2afe08aa83" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PartnersCapitalandDistributionsPAADistributionsDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#PartnersCapitalandDistributionsPAADistributionsDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PartnersCapitalandDistributionsPAADistributionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_cc227b1d-e524-4d38-86b8-0f0cf343a710" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_cc227b1d-e524-4d38-86b8-0f0cf343a710" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_cc227b1d-e524-4d38-86b8-0f0cf343a710_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_cc227b1d-e524-4d38-86b8-0f0cf343a710" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_cc227b1d-e524-4d38-86b8-0f0cf343a710_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_cff14a48-66cc-4816-a949-6d2dd3df7cdd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_cc227b1d-e524-4d38-86b8-0f0cf343a710" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_cff14a48-66cc-4816-a949-6d2dd3df7cdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_9badce6d-5a42-4098-932e-71676cb67019" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_cff14a48-66cc-4816-a949-6d2dd3df7cdd" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_9badce6d-5a42-4098-932e-71676cb67019" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_bbfce0a5-6959-4868-8de6-294405a3e003" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:to="loc_srt_CounterpartyNameAxis_bbfce0a5-6959-4868-8de6-294405a3e003" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_bbfce0a5-6959-4868-8de6-294405a3e003_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_bbfce0a5-6959-4868-8de6-294405a3e003" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_bbfce0a5-6959-4868-8de6-294405a3e003_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_f6783d18-e8b0-4a9f-9215-1ed3b729e9b1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_bbfce0a5-6959-4868-8de6-294405a3e003" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_f6783d18-e8b0-4a9f-9215-1ed3b729e9b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PublicUnitHoldersMember_12a64866-ed5e-4323-bdd8-0b9a5797a11d" xlink:href="pagp-20231231.xsd#pagp_PublicUnitHoldersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_f6783d18-e8b0-4a9f-9215-1ed3b729e9b1" xlink:to="loc_pagp_PublicUnitHoldersMember_12a64866-ed5e-4323-bdd8-0b9a5797a11d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_699d1b82-a3d4-4a61-b71d-6c2ad631154b" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_f6783d18-e8b0-4a9f-9215-1ed3b729e9b1" xlink:to="loc_pagp_PlainsAAPLPMember_699d1b82-a3d4-4a61-b71d-6c2ad631154b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_d5b87e61-b7ce-458c-baf8-77eeb8494ac7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:to="loc_us-gaap_DividendsAxis_d5b87e61-b7ce-458c-baf8-77eeb8494ac7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_d5b87e61-b7ce-458c-baf8-77eeb8494ac7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_d5b87e61-b7ce-458c-baf8-77eeb8494ac7" xlink:to="loc_us-gaap_DividendsDomain_d5b87e61-b7ce-458c-baf8-77eeb8494ac7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_d86b74d1-b0c3-4de1-b59b-52e734145d90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_d5b87e61-b7ce-458c-baf8-77eeb8494ac7" xlink:to="loc_us-gaap_DividendsDomain_d86b74d1-b0c3-4de1-b59b-52e734145d90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_FourthQuarterDistributionMember_c3e233d1-9040-4c26-baaf-6032d858440b" xlink:href="pagp-20231231.xsd#pagp_FourthQuarterDistributionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsDomain_d86b74d1-b0c3-4de1-b59b-52e734145d90" xlink:to="loc_pagp_FourthQuarterDistributionMember_c3e233d1-9040-4c26-baaf-6032d858440b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_e0b3bc1e-ed46-4f32-95a5-ff89129c56a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:to="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_e0b3bc1e-ed46-4f32-95a5-ff89129c56a5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionTypeDomain_e0b3bc1e-ed46-4f32-95a5-ff89129c56a5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_e0b3bc1e-ed46-4f32-95a5-ff89129c56a5" xlink:to="loc_us-gaap_DistributionTypeDomain_e0b3bc1e-ed46-4f32-95a5-ff89129c56a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionTypeDomain_dba22a76-6107-44e4-bbb1-7f3450415813" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_e0b3bc1e-ed46-4f32-95a5-ff89129c56a5" xlink:to="loc_us-gaap_DistributionTypeDomain_dba22a76-6107-44e4-bbb1-7f3450415813" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashDistributionMember_eaa1cb91-3559-408b-8cc0-5aa17a5e8dd6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashDistributionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DistributionTypeDomain_dba22a76-6107-44e4-bbb1-7f3450415813" xlink:to="loc_us-gaap_CashDistributionMember_eaa1cb91-3559-408b-8cc0-5aa17a5e8dd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_054bb413-bbce-4799-b593-7b66dc6fcfc6" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:to="loc_dei_LegalEntityAxis_054bb413-bbce-4799-b593-7b66dc6fcfc6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_054bb413-bbce-4799-b593-7b66dc6fcfc6_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_054bb413-bbce-4799-b593-7b66dc6fcfc6" xlink:to="loc_dei_EntityDomain_054bb413-bbce-4799-b593-7b66dc6fcfc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_3ce6dc05-358a-4a03-bd4f-204dd33642d3" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_054bb413-bbce-4799-b593-7b66dc6fcfc6" xlink:to="loc_dei_EntityDomain_3ce6dc05-358a-4a03-bd4f-204dd33642d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_688a70d7-f78c-4c19-a2dd-83884da9c500" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_3ce6dc05-358a-4a03-bd4f-204dd33642d3" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_688a70d7-f78c-4c19-a2dd-83884da9c500" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_03005b6b-7e98-4a3f-a82b-1f685c8d1392" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_03005b6b-7e98-4a3f-a82b-1f685c8d1392" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_03005b6b-7e98-4a3f-a82b-1f685c8d1392_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_03005b6b-7e98-4a3f-a82b-1f685c8d1392" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_03005b6b-7e98-4a3f-a82b-1f685c8d1392_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_dde21bd0-725d-4c4c-8897-969542c72f45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_03005b6b-7e98-4a3f-a82b-1f685c8d1392" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_dde21bd0-725d-4c4c-8897-969542c72f45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeriesAPreferredUnitsMember_b5670934-3896-41a8-9186-e2f6de2e13c9" xlink:href="pagp-20231231.xsd#pagp_SeriesAPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_dde21bd0-725d-4c4c-8897-969542c72f45" xlink:to="loc_pagp_SeriesAPreferredUnitsMember_b5670934-3896-41a8-9186-e2f6de2e13c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CommonUnitsMember_aa595770-8674-47cf-a553-7e2c5b220eed" xlink:href="pagp-20231231.xsd#pagp_CommonUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_dde21bd0-725d-4c4c-8897-969542c72f45" xlink:to="loc_pagp_CommonUnitsMember_aa595770-8674-47cf-a553-7e2c5b220eed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SeriesBPreferredUnitsMember_1a8a68d8-a279-47db-9c94-479b3d6adf14" xlink:href="pagp-20231231.xsd#pagp_SeriesBPreferredUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_dde21bd0-725d-4c4c-8897-969542c72f45" xlink:to="loc_pagp_SeriesBPreferredUnitsMember_1a8a68d8-a279-47db-9c94-479b3d6adf14" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_265c0720-eece-40ec-9076-a3cdc8993ffc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_8ca74077-f08a-4a08-b2ee-39f37ae6b04b" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_265c0720-eece-40ec-9076-a3cdc8993ffc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_265c0720-eece-40ec-9076-a3cdc8993ffc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_265c0720-eece-40ec-9076-a3cdc8993ffc" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_265c0720-eece-40ec-9076-a3cdc8993ffc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_69d11861-d7cf-4096-a96c-b2a6ec0e81e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_265c0720-eece-40ec-9076-a3cdc8993ffc" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_69d11861-d7cf-4096-a96c-b2a6ec0e81e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_7fe66d1e-aad4-4b37-bfab-1619f4d2b604" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_69d11861-d7cf-4096-a96c-b2a6ec0e81e4" xlink:to="loc_us-gaap_SubsequentEventMember_7fe66d1e-aad4-4b37-bfab-1619f4d2b604" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PreferredUnitsDistributionRateResetBasisSpreadOnVariableRate_e7104c43-c24d-45b5-8b09-2a72d8f68792" xlink:href="pagp-20231231.xsd#pagp_PreferredUnitsDistributionRateResetBasisSpreadOnVariableRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_pagp_PreferredUnitsDistributionRateResetBasisSpreadOnVariableRate_e7104c43-c24d-45b5-8b09-2a72d8f68792" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PreferredUnitsQuarterlyDistributionsPerUnit_ba189d8e-64e3-40df-ba2c-ea0396a34782" xlink:href="pagp-20231231.xsd#pagp_PreferredUnitsQuarterlyDistributionsPerUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_pagp_PreferredUnitsQuarterlyDistributionsPerUnit_ba189d8e-64e3-40df-ba2c-ea0396a34782" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_056c9d8f-3624-4c3d-99a7-d946d76a110f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_056c9d8f-3624-4c3d-99a7-d946d76a110f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStock_79ff04a3-1879-4689-bbf9-070e957b9de6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_us-gaap_DividendsPreferredStock_79ff04a3-1879-4689-bbf9-070e957b9de6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_4f075e19-efe7-406a-a6e2-9b0885a305a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_4f075e19-efe7-406a-a6e2-9b0885a305a2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendRatePercentage_e04b1f6a-bf32-467c-bb7d-f3d61352444f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_us-gaap_PreferredStockDividendRatePercentage_e04b1f6a-bf32-467c-bb7d-f3d61352444f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendRatePerDollarAmount_6f1ba4d3-4afd-4d61-9aa4-7cdb3296484e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendRatePerDollarAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_us-gaap_PreferredStockDividendRatePerDollarAmount_6f1ba4d3-4afd-4d61-9aa4-7cdb3296484e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PreferredUnitDistributionPercentageSpread_24af7f8b-b78d-4a97-b078-ddf6e3a3f6e6" xlink:href="pagp-20231231.xsd#pagp_PreferredUnitDistributionPercentageSpread"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_pagp_PreferredUnitDistributionPercentageSpread_24af7f8b-b78d-4a97-b078-ddf6e3a3f6e6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PreferredUnitDistributionPercentageCreditSpreadAdjustment_3dca3d0d-d011-4a3d-8d59-d9dcecdfca4d" xlink:href="pagp-20231231.xsd#pagp_PreferredUnitDistributionPercentageCreditSpreadAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_pagp_PreferredUnitDistributionPercentageCreditSpreadAdjustment_3dca3d0d-d011-4a3d-8d59-d9dcecdfca4d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NumberOfDaysRequiredForDistributionToUnitholdersAfterEndOfQuarter_f74af238-cdeb-4526-9777-814ca96a0514" xlink:href="pagp-20231231.xsd#pagp_NumberOfDaysRequiredForDistributionToUnitholdersAfterEndOfQuarter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_pagp_NumberOfDaysRequiredForDistributionToUnitholdersAfterEndOfQuarter_f74af238-cdeb-4526-9777-814ca96a0514" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit_a17b835b-46d4-4158-a696-f5b25c980a4c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit_a17b835b-46d4-4158-a696-f5b25c980a4c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit_89935e07-2ecf-4741-bad5-fe35c7a6617d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit_89935e07-2ecf-4741-bad5-fe35c7a6617d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountDistributions_a75e6f42-b052-4e09-afa3-e55689075f71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_e2598cae-a760-471b-9f74-4c07bb4841a7" xlink:to="loc_us-gaap_PartnersCapitalAccountDistributions_a75e6f42-b052-4e09-afa3-e55689075f71" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PartnersCapitalandDistributionsAAPDistributionsDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#PartnersCapitalandDistributionsAAPDistributionsDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PartnersCapitalandDistributionsAAPDistributionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionLineItems_ce01a03d-498a-48bd-8fc4-aa6238b0a31b" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionsTable_eac56c97-5b55-48d1-8611-05038028323d" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_ce01a03d-498a-48bd-8fc4-aa6238b0a31b" xlink:to="loc_pagp_PartnersCapitalAndDistributionsTable_eac56c97-5b55-48d1-8611-05038028323d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_7e5f1583-eb43-459d-9606-8d4dd24ea555" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_eac56c97-5b55-48d1-8611-05038028323d" xlink:to="loc_us-gaap_DividendsAxis_7e5f1583-eb43-459d-9606-8d4dd24ea555" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_7e5f1583-eb43-459d-9606-8d4dd24ea555_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_7e5f1583-eb43-459d-9606-8d4dd24ea555" xlink:to="loc_us-gaap_DividendsDomain_7e5f1583-eb43-459d-9606-8d4dd24ea555_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_7a81277d-450c-48b3-9f96-2207f756c65f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_7e5f1583-eb43-459d-9606-8d4dd24ea555" xlink:to="loc_us-gaap_DividendsDomain_7a81277d-450c-48b3-9f96-2207f756c65f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_FourthQuarterDistributionMember_8e623e2e-7ba8-4457-9332-7d67cba9b69a" xlink:href="pagp-20231231.xsd#pagp_FourthQuarterDistributionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsDomain_7a81277d-450c-48b3-9f96-2207f756c65f" xlink:to="loc_pagp_FourthQuarterDistributionMember_8e623e2e-7ba8-4457-9332-7d67cba9b69a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_5e787f3a-8c0a-40dd-9164-2ee6b7a6c8bb" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_eac56c97-5b55-48d1-8611-05038028323d" xlink:to="loc_dei_LegalEntityAxis_5e787f3a-8c0a-40dd-9164-2ee6b7a6c8bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_5e787f3a-8c0a-40dd-9164-2ee6b7a6c8bb_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_5e787f3a-8c0a-40dd-9164-2ee6b7a6c8bb" xlink:to="loc_dei_EntityDomain_5e787f3a-8c0a-40dd-9164-2ee6b7a6c8bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_cef09d0f-e653-423e-ab5a-369ae6714ec7" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_5e787f3a-8c0a-40dd-9164-2ee6b7a6c8bb" xlink:to="loc_dei_EntityDomain_cef09d0f-e653-423e-ab5a-369ae6714ec7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_cd6b787a-9915-432d-b49c-1bbb226b9580" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_cef09d0f-e653-423e-ab5a-369ae6714ec7" xlink:to="loc_pagp_PlainsAAPLPMember_cd6b787a-9915-432d-b49c-1bbb226b9580" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_2451a649-132b-4f3d-826b-1643a3638b71" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_cef09d0f-e653-423e-ab5a-369ae6714ec7" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_2451a649-132b-4f3d-826b-1643a3638b71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_44b60062-c118-41b1-9836-014bc11e1a35" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_eac56c97-5b55-48d1-8611-05038028323d" xlink:to="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_44b60062-c118-41b1-9836-014bc11e1a35" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionTypeDomain_44b60062-c118-41b1-9836-014bc11e1a35_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_44b60062-c118-41b1-9836-014bc11e1a35" xlink:to="loc_us-gaap_DistributionTypeDomain_44b60062-c118-41b1-9836-014bc11e1a35_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionTypeDomain_bc57178c-d016-43c5-8209-22ede05d484f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_44b60062-c118-41b1-9836-014bc11e1a35" xlink:to="loc_us-gaap_DistributionTypeDomain_bc57178c-d016-43c5-8209-22ede05d484f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashDistributionMember_69ad83b1-22fb-46b6-aa15-3dae2a33da5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashDistributionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DistributionTypeDomain_bc57178c-d016-43c5-8209-22ede05d484f" xlink:to="loc_us-gaap_CashDistributionMember_69ad83b1-22fb-46b6-aa15-3dae2a33da5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_16bd45fd-24fe-40c7-aa6f-c3d15b6ed076" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_eac56c97-5b55-48d1-8611-05038028323d" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_16bd45fd-24fe-40c7-aa6f-c3d15b6ed076" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_16bd45fd-24fe-40c7-aa6f-c3d15b6ed076_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_16bd45fd-24fe-40c7-aa6f-c3d15b6ed076" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_16bd45fd-24fe-40c7-aa6f-c3d15b6ed076_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_283162a1-a549-4a6e-9904-57a4c40c0a46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_16bd45fd-24fe-40c7-aa6f-c3d15b6ed076" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_283162a1-a549-4a6e-9904-57a4c40c0a46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_f6f2861d-8c9e-4abc-b49d-2e7c7b3b6b3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_283162a1-a549-4a6e-9904-57a4c40c0a46" xlink:to="loc_us-gaap_SubsequentEventMember_f6f2861d-8c9e-4abc-b49d-2e7c7b3b6b3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_6e53f11f-0336-435c-8270-ba12935cb9d9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_eac56c97-5b55-48d1-8611-05038028323d" xlink:to="loc_srt_CounterpartyNameAxis_6e53f11f-0336-435c-8270-ba12935cb9d9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6e53f11f-0336-435c-8270-ba12935cb9d9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_6e53f11f-0336-435c-8270-ba12935cb9d9" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6e53f11f-0336-435c-8270-ba12935cb9d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_edf9e8e8-b5a7-4795-8f74-3ce7ae975592" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_6e53f11f-0336-435c-8270-ba12935cb9d9" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_edf9e8e8-b5a7-4795-8f74-3ce7ae975592" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_d2da38f7-2625-4905-be49-7e14a8f85eaa" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_edf9e8e8-b5a7-4795-8f74-3ce7ae975592" xlink:to="loc_pagp_PlainsAAPLPMember_d2da38f7-2625-4905-be49-7e14a8f85eaa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_a86ad229-0457-4ccc-9a59-50823e8649c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_eac56c97-5b55-48d1-8611-05038028323d" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_a86ad229-0457-4ccc-9a59-50823e8649c6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_a86ad229-0457-4ccc-9a59-50823e8649c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_a86ad229-0457-4ccc-9a59-50823e8649c6" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_a86ad229-0457-4ccc-9a59-50823e8649c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c5d1b2da-5854-421a-9906-8e464abb39fa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_a86ad229-0457-4ccc-9a59-50823e8649c6" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c5d1b2da-5854-421a-9906-8e464abb39fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CommonUnitsMember_0438d99c-a87e-4036-b5d0-f738e2ed52c3" xlink:href="pagp-20231231.xsd#pagp_CommonUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_c5d1b2da-5854-421a-9906-8e464abb39fa" xlink:to="loc_pagp_CommonUnitsMember_0438d99c-a87e-4036-b5d0-f738e2ed52c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_bd35f94b-5963-4363-b1f3-92d39fa39bd2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_ce01a03d-498a-48bd-8fc4-aa6238b0a31b" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_bd35f94b-5963-4363-b1f3-92d39fa39bd2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountDistributionAmount_e1794c4a-dee9-4568-8b47-b876968e083e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountDistributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_ce01a03d-498a-48bd-8fc4-aa6238b0a31b" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountDistributionAmount_e1794c4a-dee9-4568-8b47-b876968e083e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashDividendsPaidToParentCompanyByConsolidatedSubsidiaries_d0048892-a49c-4f96-aa94-b4c5b75075b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashDividendsPaidToParentCompanyByConsolidatedSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_ce01a03d-498a-48bd-8fc4-aa6238b0a31b" xlink:to="loc_us-gaap_CashDividendsPaidToParentCompanyByConsolidatedSubsidiaries_d0048892-a49c-4f96-aa94-b4c5b75075b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountDistributions_642b89c9-178d-43d2-bf88-1c69e4fc4e95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_ce01a03d-498a-48bd-8fc4-aa6238b0a31b" xlink:to="loc_us-gaap_PartnersCapitalAccountDistributions_642b89c9-178d-43d2-bf88-1c69e4fc4e95" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/PartnersCapitalandDistributionsDistributionstoNoncontrollingInterestsDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#PartnersCapitalandDistributionsDistributionstoNoncontrollingInterestsDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/PartnersCapitalandDistributionsDistributionstoNoncontrollingInterestsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionLineItems_2b20531b-651e-46d4-bfab-17cf9e8a109b" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PartnersCapitalAndDistributionsTable_6def869c-cddf-407b-afc8-6750bed1bcbb" xlink:href="pagp-20231231.xsd#pagp_PartnersCapitalAndDistributionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_2b20531b-651e-46d4-bfab-17cf9e8a109b" xlink:to="loc_pagp_PartnersCapitalAndDistributionsTable_6def869c-cddf-407b-afc8-6750bed1bcbb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_7c7d849a-ed70-4786-8523-6fb9ba0756c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_6def869c-cddf-407b-afc8-6750bed1bcbb" xlink:to="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_7c7d849a-ed70-4786-8523-6fb9ba0756c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionTypeDomain_7c7d849a-ed70-4786-8523-6fb9ba0756c9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_7c7d849a-ed70-4786-8523-6fb9ba0756c9" xlink:to="loc_us-gaap_DistributionTypeDomain_7c7d849a-ed70-4786-8523-6fb9ba0756c9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DistributionTypeDomain_b8674c27-b0d7-43b1-81ab-a4f8dfc885e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DistributionTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis_7c7d849a-ed70-4786-8523-6fb9ba0756c9" xlink:to="loc_us-gaap_DistributionTypeDomain_b8674c27-b0d7-43b1-81ab-a4f8dfc885e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashDistributionMember_26bb91c4-7cdc-4b30-9b37-a6f8636359a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashDistributionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DistributionTypeDomain_b8674c27-b0d7-43b1-81ab-a4f8dfc885e1" xlink:to="loc_us-gaap_CashDistributionMember_26bb91c4-7cdc-4b30-9b37-a6f8636359a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsAxis_163e15d4-27d5-4b3e-82f7-65fa18915975" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_6def869c-cddf-407b-afc8-6750bed1bcbb" xlink:to="loc_us-gaap_PartnerCapitalComponentsAxis_163e15d4-27d5-4b3e-82f7-65fa18915975" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_163e15d4-27d5-4b3e-82f7-65fa18915975_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_163e15d4-27d5-4b3e-82f7-65fa18915975" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_163e15d4-27d5-4b3e-82f7-65fa18915975_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_71cbd099-6c7b-4cbf-aa13-6d23c0293a21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnerCapitalComponentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_163e15d4-27d5-4b3e-82f7-65fa18915975" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_71cbd099-6c7b-4cbf-aa13-6d23c0293a21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_9c2e8ba8-f0a0-4eb4-a9a9-a8f1b37222f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_71cbd099-6c7b-4cbf-aa13-6d23c0293a21" xlink:to="loc_us-gaap_NoncontrollingInterestMember_9c2e8ba8-f0a0-4eb4-a9a9-a8f1b37222f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_32bae688-13b1-44ed-9165-eea80316dcac" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_6def869c-cddf-407b-afc8-6750bed1bcbb" xlink:to="loc_dei_LegalEntityAxis_32bae688-13b1-44ed-9165-eea80316dcac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_32bae688-13b1-44ed-9165-eea80316dcac_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_32bae688-13b1-44ed-9165-eea80316dcac" xlink:to="loc_dei_EntityDomain_32bae688-13b1-44ed-9165-eea80316dcac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_23805608-b935-40de-a348-788bca8ca7a6" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_32bae688-13b1-44ed-9165-eea80316dcac" xlink:to="loc_dei_EntityDomain_23805608-b935-40de-a348-788bca8ca7a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsOryxPermianBasinLLCMember_081564bb-ca53-4a3c-9d68-c89e06c8c42e" xlink:href="pagp-20231231.xsd#pagp_PlainsOryxPermianBasinLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_23805608-b935-40de-a348-788bca8ca7a6" xlink:to="loc_pagp_PlainsOryxPermianBasinLLCMember_081564bb-ca53-4a3c-9d68-c89e06c8c42e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CactusIIPipelineLLCMember_bac0804e-5942-44db-a314-1443d9cf988d" xlink:href="pagp-20231231.xsd#pagp_CactusIIPipelineLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_23805608-b935-40de-a348-788bca8ca7a6" xlink:to="loc_pagp_CactusIIPipelineLLCMember_bac0804e-5942-44db-a314-1443d9cf988d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_RedRiverPipelineCompanyLLCMember_a4ce868c-6337-4360-bb6c-5bda2a20f45a" xlink:href="pagp-20231231.xsd#pagp_RedRiverPipelineCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_23805608-b935-40de-a348-788bca8ca7a6" xlink:to="loc_pagp_RedRiverPipelineCompanyLLCMember_a4ce868c-6337-4360-bb6c-5bda2a20f45a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_52baee01-f490-4fad-819c-acdb845b2f82" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_PartnersCapitalAndDistributionsTable_6def869c-cddf-407b-afc8-6750bed1bcbb" xlink:to="loc_srt_ConsolidatedEntitiesAxis_52baee01-f490-4fad-819c-acdb845b2f82" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_52baee01-f490-4fad-819c-acdb845b2f82_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_52baee01-f490-4fad-819c-acdb845b2f82" xlink:to="loc_srt_ConsolidatedEntitiesDomain_52baee01-f490-4fad-819c-acdb845b2f82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_109489a3-c6ce-4497-9fb6-34709bd43aeb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_52baee01-f490-4fad-819c-acdb845b2f82" xlink:to="loc_srt_ConsolidatedEntitiesDomain_109489a3-c6ce-4497-9fb6-34709bd43aeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ConsolidatedJointVentureEntitiesMember_d89fe6d4-e943-4f02-ba2f-326c066c8379" xlink:href="pagp-20231231.xsd#pagp_ConsolidatedJointVentureEntitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_109489a3-c6ce-4497-9fb6-34709bd43aeb" xlink:to="loc_pagp_ConsolidatedJointVentureEntitiesMember_d89fe6d4-e943-4f02-ba2f-326c066c8379" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountDistributions_219aee87-2b28-4baf-acfe-8fb305ed3744" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnersCapitalAccountDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_PartnersCapitalAndDistributionLineItems_2b20531b-651e-46d4-bfab-17cf9e8a109b" xlink:to="loc_us-gaap_PartnersCapitalAccountDistributions_219aee87-2b28-4baf-acfe-8fb305ed3744" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesCommodityPriceRiskHedgingDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesCommodityPriceRiskHedgingDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesCommodityPriceRiskHedgingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_2b038865-3cb8-4ac3-9aaf-f974f5f2a0e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_d295fd8f-28d7-4f12-aea1-b2260a947c1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_2b038865-3cb8-4ac3-9aaf-f974f5f2a0e4" xlink:to="loc_us-gaap_DerivativeTable_d295fd8f-28d7-4f12-aea1-b2260a947c1f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_7944c132-f879-42a5-8f4f-1c8f1517b517" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_d295fd8f-28d7-4f12-aea1-b2260a947c1f" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_7944c132-f879-42a5-8f4f-1c8f1517b517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_7944c132-f879-42a5-8f4f-1c8f1517b517_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_7944c132-f879-42a5-8f4f-1c8f1517b517" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_7944c132-f879-42a5-8f4f-1c8f1517b517_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_528a622b-ec9f-40b7-adda-9d4e9f236020" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_7944c132-f879-42a5-8f4f-1c8f1517b517" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_528a622b-ec9f-40b7-adda-9d4e9f236020" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_528a622b-ec9f-40b7-adda-9d4e9f236020" xlink:to="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractsRelatedToCrudeOilPurchasesMember_ee787731-3702-4326-9b03-694f107f19eb" xlink:href="pagp-20231231.xsd#pagp_ContractsRelatedToCrudeOilPurchasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_ContractsRelatedToCrudeOilPurchasesMember_ee787731-3702-4326-9b03-694f107f19eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_TimeSpreadOnHedgeAnticipatedCrudeOilLeaseGatheringPurchaseContractsMember_04b8ca4e-31af-417d-a116-93ea667d898c" xlink:href="pagp-20231231.xsd#pagp_TimeSpreadOnHedgeAnticipatedCrudeOilLeaseGatheringPurchaseContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_TimeSpreadOnHedgeAnticipatedCrudeOilLeaseGatheringPurchaseContractsMember_04b8ca4e-31af-417d-a116-93ea667d898c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilBasisSpreadPositionMember_bcf75782-97be-4a89-a8bf-123030ab30e6" xlink:href="pagp-20231231.xsd#pagp_CrudeOilBasisSpreadPositionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_CrudeOilBasisSpreadPositionMember_bcf75782-97be-4a89-a8bf-123030ab30e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AnticipatedNetSalesOfInventoryMember_5b5c39ef-6e43-4c86-968d-ecc9e0558c5e" xlink:href="pagp-20231231.xsd#pagp_AnticipatedNetSalesOfInventoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_AnticipatedNetSalesOfInventoryMember_5b5c39ef-6e43-4c86-968d-ecc9e0558c5e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ContractsRelatedToNaturalGasPurchasesMember_95c56a31-d156-4bed-97cb-71605ff03b57" xlink:href="pagp-20231231.xsd#pagp_ContractsRelatedToNaturalGasPurchasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_ContractsRelatedToNaturalGasPurchasesMember_95c56a31-d156-4bed-97cb-71605ff03b57" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PropaneContractsRelatedToSubsequentSaleOfProductMember_c67eb79f-9f75-44cb-a604-3ef80da6b008" xlink:href="pagp-20231231.xsd#pagp_PropaneContractsRelatedToSubsequentSaleOfProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_PropaneContractsRelatedToSubsequentSaleOfProductMember_c67eb79f-9f75-44cb-a604-3ef80da6b008" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ButaneContractsRelatedToSubsequentSaleOfProductMember_ef2e37e1-4cb3-403e-82cf-eab48df6a703" xlink:href="pagp-20231231.xsd#pagp_ButaneContractsRelatedToSubsequentSaleOfProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_ButaneContractsRelatedToSubsequentSaleOfProductMember_ef2e37e1-4cb3-403e-82cf-eab48df6a703" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CondensateContractsRelatedToSubsequentSaleOfProductMember_50a0defe-3ca0-44f6-8212-cae123beba2c" xlink:href="pagp-20231231.xsd#pagp_CondensateContractsRelatedToSubsequentSaleOfProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_CondensateContractsRelatedToSubsequentSaleOfProductMember_50a0defe-3ca0-44f6-8212-cae123beba2c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_FuelGasRequirementsContractsMember_82818564-adb2-40b0-8cb5-ce837f8f452a" xlink:href="pagp-20231231.xsd#pagp_FuelGasRequirementsContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_FuelGasRequirementsContractsMember_82818564-adb2-40b0-8cb5-ce837f8f452a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PowerSupplyRequirementsContractsMember_22dfce40-f26c-401d-ae86-e7514ba8a2c4" xlink:href="pagp-20231231.xsd#pagp_PowerSupplyRequirementsContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CommodityContractMember_9c211906-7c01-4622-897a-d38eee026681" xlink:to="loc_pagp_PowerSupplyRequirementsContractsMember_22dfce40-f26c-401d-ae86-e7514ba8a2c4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionAxis_d6323180-d423-41f3-8edf-5d6694a4f4e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PositionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_d295fd8f-28d7-4f12-aea1-b2260a947c1f" xlink:to="loc_us-gaap_PositionAxis_d6323180-d423-41f3-8edf-5d6694a4f4e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_d6323180-d423-41f3-8edf-5d6694a4f4e0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_d6323180-d423-41f3-8edf-5d6694a4f4e0" xlink:to="loc_us-gaap_PositionDomain_d6323180-d423-41f3-8edf-5d6694a4f4e0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_7e01d291-cf90-4529-b17f-6d83b663b05d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_d6323180-d423-41f3-8edf-5d6694a4f4e0" xlink:to="loc_us-gaap_PositionDomain_7e01d291-cf90-4529-b17f-6d83b663b05d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongMember_303032be-48ac-4985-801b-01fc80f3b69d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_7e01d291-cf90-4529-b17f-6d83b663b05d" xlink:to="loc_us-gaap_LongMember_303032be-48ac-4985-801b-01fc80f3b69d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortMember_65680881-58a2-46a9-9deb-7a302f2ab992" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_7e01d291-cf90-4529-b17f-6d83b663b05d" xlink:to="loc_us-gaap_ShortMember_65680881-58a2-46a9-9deb-7a302f2ab992" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PriceRiskDerivativesAbstract_87f9d984-e3c6-4859-aa2a-39ece3661b1c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PriceRiskDerivativesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_2b038865-3cb8-4ac3-9aaf-f974f5f2a0e4" xlink:to="loc_us-gaap_PriceRiskDerivativesAbstract_87f9d984-e3c6-4859-aa2a-39ece3661b1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_68c2c1ca-8860-4bbc-b62c-ae0275709084" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountVolume"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PriceRiskDerivativesAbstract_87f9d984-e3c6-4859-aa2a-39ece3661b1c" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_68c2c1ca-8860-4bbc-b62c-ae0275709084" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_5874a263-1b99-4939-b7bb-42cb050c7aeb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PriceRiskDerivativesAbstract_87f9d984-e3c6-4859-aa2a-39ece3661b1c" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_5874a263-1b99-4939-b7bb-42cb050c7aeb" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesFinancialImpactDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesFinancialImpactDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesFinancialImpactDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_053ed2d5-f408-4c24-9e37-0fedcd800f6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_c6091138-6a69-456c-b625-53c360d7991b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_053ed2d5-f408-4c24-9e37-0fedcd800f6e" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_c6091138-6a69-456c-b625-53c360d7991b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_a9d6e5c9-0bd9-4cd7-b4fc-e0b8409ea1ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_c6091138-6a69-456c-b625-53c360d7991b" xlink:to="loc_us-gaap_HedgingDesignationAxis_a9d6e5c9-0bd9-4cd7-b4fc-e0b8409ea1ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_a9d6e5c9-0bd9-4cd7-b4fc-e0b8409ea1ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_a9d6e5c9-0bd9-4cd7-b4fc-e0b8409ea1ca" xlink:to="loc_us-gaap_HedgingDesignationDomain_a9d6e5c9-0bd9-4cd7-b4fc-e0b8409ea1ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_6f38e7ec-2709-4b51-9258-be4761ed2e1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_a9d6e5c9-0bd9-4cd7-b4fc-e0b8409ea1ca" xlink:to="loc_us-gaap_HedgingDesignationDomain_6f38e7ec-2709-4b51-9258-be4761ed2e1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_9bde1280-bdf3-403a-8c2d-5692a373cbeb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_6f38e7ec-2709-4b51-9258-be4761ed2e1f" xlink:to="loc_us-gaap_NondesignatedMember_9bde1280-bdf3-403a-8c2d-5692a373cbeb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_e0411cf2-66a2-4aee-a162-2c04cb247a22" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_c6091138-6a69-456c-b625-53c360d7991b" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_e0411cf2-66a2-4aee-a162-2c04cb247a22" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e0411cf2-66a2-4aee-a162-2c04cb247a22_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_e0411cf2-66a2-4aee-a162-2c04cb247a22" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e0411cf2-66a2-4aee-a162-2c04cb247a22_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_78424baa-67c4-4e69-97ba-1077d4c72482" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_e0411cf2-66a2-4aee-a162-2c04cb247a22" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_78424baa-67c4-4e69-97ba-1077d4c72482" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_7130e2b6-bc1e-4875-a9fc-c02a23e446c7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_78424baa-67c4-4e69-97ba-1077d4c72482" xlink:to="loc_us-gaap_CommodityContractMember_7130e2b6-bc1e-4875-a9fc-c02a23e446c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_971edfd6-9720-414d-822e-2aa76540ea9e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_c6091138-6a69-456c-b625-53c360d7991b" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_971edfd6-9720-414d-822e-2aa76540ea9e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_971edfd6-9720-414d-822e-2aa76540ea9e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_971edfd6-9720-414d-822e-2aa76540ea9e" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_971edfd6-9720-414d-822e-2aa76540ea9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_377a04f4-bb46-4085-ab59-e0144df2b6d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_971edfd6-9720-414d-822e-2aa76540ea9e" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_377a04f4-bb46-4085-ab59-e0144df2b6d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_a8fd4e6d-5479-4c29-b0e5-aff13c512048" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_377a04f4-bb46-4085-ab59-e0144df2b6d1" xlink:to="loc_us-gaap_ProductMember_a8fd4e6d-5479-4c29-b0e5-aff13c512048" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_FieldOperatingCostsMember_012cd08e-bc20-48c4-9777-fd32cc15933f" xlink:href="pagp-20231231.xsd#pagp_FieldOperatingCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_377a04f4-bb46-4085-ab59-e0144df2b6d1" xlink:to="loc_pagp_FieldOperatingCostsMember_012cd08e-bc20-48c4-9777-fd32cc15933f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_7d894638-ad61-40f7-bbed-3c6e6396e007" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_053ed2d5-f408-4c24-9e37-0fedcd800f6e" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_7d894638-ad61-40f7-bbed-3c6e6396e007" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesBrokerReceivablePayableDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesBrokerReceivablePayableDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesBrokerReceivablePayableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_a573fcb8-d0ba-4db5-9058-23165fe1551a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_39f7f96d-5d31-47b2-a76c-63e5219b6055" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a573fcb8-d0ba-4db5-9058-23165fe1551a" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_39f7f96d-5d31-47b2-a76c-63e5219b6055" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionTypeAxis_aaca1385-aafc-45ec-b3d0-2a672bdac073" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_39f7f96d-5d31-47b2-a76c-63e5219b6055" xlink:to="loc_us-gaap_TransactionTypeAxis_aaca1385-aafc-45ec-b3d0-2a672bdac073" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_aaca1385-aafc-45ec-b3d0-2a672bdac073_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TransactionTypeAxis_aaca1385-aafc-45ec-b3d0-2a672bdac073" xlink:to="loc_us-gaap_TransactionDomain_aaca1385-aafc-45ec-b3d0-2a672bdac073_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransactionDomain_8cce5b0c-5eb8-4b25-ac40-5470e255e8a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TransactionTypeAxis_aaca1385-aafc-45ec-b3d0-2a672bdac073" xlink:to="loc_us-gaap_TransactionDomain_8cce5b0c-5eb8-4b25-ac40-5470e255e8a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExchangeTradedMember_69fb97e7-948c-4604-8359-fcd3fe851a97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExchangeTradedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransactionDomain_8cce5b0c-5eb8-4b25-ac40-5470e255e8a5" xlink:to="loc_us-gaap_ExchangeTradedMember_69fb97e7-948c-4604-8359-fcd3fe851a97" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InitialMargin_58d35a36-af76-464f-be8d-2c2dbe4b9cc7" xlink:href="pagp-20231231.xsd#pagp_InitialMargin"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a573fcb8-d0ba-4db5-9058-23165fe1551a" xlink:to="loc_pagp_InitialMargin_58d35a36-af76-464f-be8d-2c2dbe4b9cc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_VariationMarginPostedReturned_78bbe42e-fd6d-46ab-9b33-ce791b69923f" xlink:href="pagp-20231231.xsd#pagp_VariationMarginPostedReturned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a573fcb8-d0ba-4db5-9058-23165fe1551a" xlink:to="loc_pagp_VariationMarginPostedReturned_78bbe42e-fd6d-46ab-9b33-ce791b69923f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_3ac44290-8dd7-4f12-b24d-d7f91d6c069b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a573fcb8-d0ba-4db5-9058-23165fe1551a" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_3ac44290-8dd7-4f12-b24d-d7f91d6c069b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset_f3d4a71b-039c-4bec-84c3-5b2b225aaf5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a573fcb8-d0ba-4db5-9058-23165fe1551a" xlink:to="loc_us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset_f3d4a71b-039c-4bec-84c3-5b2b225aaf5c" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesOffsettingAssetandLiabilitiesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesOffsettingAssetandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesOffsettingAssetandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OffsettingAssetsLiabilitiesLineItems_2ed51c90-943f-47d4-a89c-65e3d4fa2d5b" xlink:href="pagp-20231231.xsd#pagp_OffsettingAssetsLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_OffsettingAssetsLiabilitiesTable_2d67d9f9-8467-46d4-818d-ee7c49c30ce8" xlink:href="pagp-20231231.xsd#pagp_OffsettingAssetsLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pagp_OffsettingAssetsLiabilitiesLineItems_2ed51c90-943f-47d4-a89c-65e3d4fa2d5b" xlink:to="loc_pagp_OffsettingAssetsLiabilitiesTable_2d67d9f9-8467-46d4-818d-ee7c49c30ce8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_4ac26d18-066b-4488-a6f9-ea2f0bd1e485" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_OffsettingAssetsLiabilitiesTable_2d67d9f9-8467-46d4-818d-ee7c49c30ce8" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_4ac26d18-066b-4488-a6f9-ea2f0bd1e485" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_4ac26d18-066b-4488-a6f9-ea2f0bd1e485_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_4ac26d18-066b-4488-a6f9-ea2f0bd1e485" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_4ac26d18-066b-4488-a6f9-ea2f0bd1e485_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_93674544-1c91-4012-ad7c-4b42de68ecbb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_4ac26d18-066b-4488-a6f9-ea2f0bd1e485" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_93674544-1c91-4012-ad7c-4b42de68ecbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_c95c16bf-6984-40cd-aab8-9432752d3d49" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_93674544-1c91-4012-ad7c-4b42de68ecbb" xlink:to="loc_us-gaap_CommodityContractMember_c95c16bf-6984-40cd-aab8-9432752d3d49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_a74c5d60-2a6e-4359-bed1-1fc82864914a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pagp_OffsettingAssetsLiabilitiesTable_2d67d9f9-8467-46d4-818d-ee7c49c30ce8" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_a74c5d60-2a6e-4359-bed1-1fc82864914a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_a74c5d60-2a6e-4359-bed1-1fc82864914a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_a74c5d60-2a6e-4359-bed1-1fc82864914a" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_a74c5d60-2a6e-4359-bed1-1fc82864914a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_066b4ee8-7d6f-47b7-8ae8-b860c0d71fd6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_a74c5d60-2a6e-4359-bed1-1fc82864914a" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_066b4ee8-7d6f-47b7-8ae8-b860c0d71fd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_09f3a4f1-2c42-4b7a-a694-54b8dcb48bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_066b4ee8-7d6f-47b7-8ae8-b860c0d71fd6" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_09f3a4f1-2c42-4b7a-a694-54b8dcb48bdc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_3cd91ada-8132-488e-8db2-8f01919a2290" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_066b4ee8-7d6f-47b7-8ae8-b860c0d71fd6" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_3cd91ada-8132-488e-8db2-8f01919a2290" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_7d150078-88b2-4945-b018-64af7a29c600" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_066b4ee8-7d6f-47b7-8ae8-b860c0d71fd6" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_7d150078-88b2-4945-b018-64af7a29c600" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_0a5b8d5b-5074-4e00-b200-52c4214305a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_066b4ee8-7d6f-47b7-8ae8-b860c0d71fd6" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_0a5b8d5b-5074-4e00-b200-52c4214305a0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingAbstract_f0d81123-68e3-4cc7-a2fb-9f08531c7395" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OffsettingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_OffsettingAssetsLiabilitiesLineItems_2ed51c90-943f-47d4-a89c-65e3d4fa2d5b" xlink:to="loc_us-gaap_OffsettingAbstract_f0d81123-68e3-4cc7-a2fb-9f08531c7395" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeAssetsAbstract_f535c9cd-d15b-406c-98e7-94a1cd0a66ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OffsettingDerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAbstract_f0d81123-68e3-4cc7-a2fb-9f08531c7395" xlink:to="loc_us-gaap_OffsettingDerivativeAssetsAbstract_f535c9cd-d15b-406c-98e7-94a1cd0a66ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_adb53180-f245-4280-bc1c-f4804725a9e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_f535c9cd-d15b-406c-98e7-94a1cd0a66ee" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_adb53180-f245-4280-bc1c-f4804725a9e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_8e655617-e18c-4523-a685-e516f251734b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_f535c9cd-d15b-406c-98e7-94a1cd0a66ee" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_8e655617-e18c-4523-a685-e516f251734b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset_efa52934-36d3-44b0-8606-c46ddedc4022" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_f535c9cd-d15b-406c-98e7-94a1cd0a66ee" xlink:to="loc_us-gaap_DerivativeAssetCollateralObligationToReturnCashOffset_efa52934-36d3-44b0-8606-c46ddedc4022" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_d72eab88-fa01-42ee-b4e0-ab3fe882480a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeAssetsAbstract_f535c9cd-d15b-406c-98e7-94a1cd0a66ee" xlink:to="loc_us-gaap_DerivativeAssets_d72eab88-fa01-42ee-b4e0-ab3fe882480a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_50d6c17a-5721-4827-9e00-996524076e98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OffsettingDerivativeLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAbstract_f0d81123-68e3-4cc7-a2fb-9f08531c7395" xlink:to="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_50d6c17a-5721-4827-9e00-996524076e98" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_023a7fe8-2c76-49cc-a0a5-540068180568" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_50d6c17a-5721-4827-9e00-996524076e98" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_023a7fe8-2c76-49cc-a0a5-540068180568" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_4700d352-0211-4671-b387-ccb928ec0299" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_50d6c17a-5721-4827-9e00-996524076e98" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_4700d352-0211-4671-b387-ccb928ec0299" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_b23b003d-bfc7-4f83-8e21-fa49be70b18b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingDerivativeLiabilitiesAbstract_50d6c17a-5721-4827-9e00-996524076e98" xlink:to="loc_us-gaap_DerivativeLiabilities_b23b003d-bfc7-4f83-8e21-fa49be70b18b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_09f71d64-b68e-471a-aae8-e365fbffb219" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OffsettingAbstract_f0d81123-68e3-4cc7-a2fb-9f08531c7395" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_09f71d64-b68e-471a-aae8-e365fbffb219" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesInterestRateRiskHedgingDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesInterestRateRiskHedgingDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesInterestRateRiskHedgingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_a6db1061-79fc-483c-9da0-64e67fb146c5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_a24b0608-9423-4dd9-8b25-6d2391457e25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_a6db1061-79fc-483c-9da0-64e67fb146c5" xlink:to="loc_us-gaap_DerivativeTable_a24b0608-9423-4dd9-8b25-6d2391457e25" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_708208fe-93b8-42cf-a904-ac428603d7d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_a24b0608-9423-4dd9-8b25-6d2391457e25" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_708208fe-93b8-42cf-a904-ac428603d7d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_708208fe-93b8-42cf-a904-ac428603d7d8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_708208fe-93b8-42cf-a904-ac428603d7d8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_708208fe-93b8-42cf-a904-ac428603d7d8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_fafa90cf-73ec-46c4-809f-2b88dccc7523" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_708208fe-93b8-42cf-a904-ac428603d7d8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_fafa90cf-73ec-46c4-809f-2b88dccc7523" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_78c2d4e8-d54a-4a39-b4f4-6b382c8621eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_fafa90cf-73ec-46c4-809f-2b88dccc7523" xlink:to="loc_us-gaap_InterestRateContractMember_78c2d4e8-d54a-4a39-b4f4-6b382c8621eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EightForwardStartingThirtyYearInterestRateSwaps309PercentMember_d77274f8-bb4d-49c7-98e1-ac3a992151c1" xlink:href="pagp-20231231.xsd#pagp_EightForwardStartingThirtyYearInterestRateSwaps309PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestRateContractMember_78c2d4e8-d54a-4a39-b4f4-6b382c8621eb" xlink:to="loc_pagp_EightForwardStartingThirtyYearInterestRateSwaps309PercentMember_d77274f8-bb4d-49c7-98e1-ac3a992151c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_FourForwardStartingThirtyYearInterestRateSwaps074PercentMember_5bf9772b-eed9-41dd-9eb0-0cb1036e95e0" xlink:href="pagp-20231231.xsd#pagp_FourForwardStartingThirtyYearInterestRateSwaps074PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestRateContractMember_78c2d4e8-d54a-4a39-b4f4-6b382c8621eb" xlink:to="loc_pagp_FourForwardStartingThirtyYearInterestRateSwaps074PercentMember_5bf9772b-eed9-41dd-9eb0-0cb1036e95e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_0d8f4ddb-e5cf-4ee8-b7fe-ad07e704658b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_a24b0608-9423-4dd9-8b25-6d2391457e25" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_0d8f4ddb-e5cf-4ee8-b7fe-ad07e704658b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_0d8f4ddb-e5cf-4ee8-b7fe-ad07e704658b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_0d8f4ddb-e5cf-4ee8-b7fe-ad07e704658b" xlink:to="loc_us-gaap_HedgingRelationshipDomain_0d8f4ddb-e5cf-4ee8-b7fe-ad07e704658b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_48a4ac03-ef21-4044-8187-a11672e915cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_0d8f4ddb-e5cf-4ee8-b7fe-ad07e704658b" xlink:to="loc_us-gaap_HedgingRelationshipDomain_48a4ac03-ef21-4044-8187-a11672e915cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_e3e19ba8-ed61-4d55-adb4-0e7bff419a23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_48a4ac03-ef21-4044-8187-a11672e915cc" xlink:to="loc_us-gaap_CashFlowHedgingMember_e3e19ba8-ed61-4d55-adb4-0e7bff419a23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateDerivativesAbstract_308d3664-8634-4fe1-8e5d-12aa3bb3f0df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateDerivativesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_a6db1061-79fc-483c-9da0-64e67fb146c5" xlink:to="loc_us-gaap_InterestRateDerivativesAbstract_308d3664-8634-4fe1-8e5d-12aa3bb3f0df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfInterestRateDerivativesHeld_e364fd9e-ec9e-4a9c-be3d-0dfe08c54a3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfInterestRateDerivativesHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestRateDerivativesAbstract_308d3664-8634-4fe1-8e5d-12aa3bb3f0df" xlink:to="loc_us-gaap_NumberOfInterestRateDerivativesHeld_e364fd9e-ec9e-4a9c-be3d-0dfe08c54a3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTermOfContract_6d9d81ae-be96-408b-8d6b-7b16ccdfd96f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestRateDerivativesAbstract_308d3664-8634-4fe1-8e5d-12aa3bb3f0df" xlink:to="loc_us-gaap_DerivativeTermOfContract_6d9d81ae-be96-408b-8d6b-7b16ccdfd96f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_5cf2bc39-b83b-4b12-a033-50e781ac572b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestRateDerivativesAbstract_308d3664-8634-4fe1-8e5d-12aa3bb3f0df" xlink:to="loc_us-gaap_DerivativeNotionalAmount_5cf2bc39-b83b-4b12-a033-50e781ac572b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_a1ab99b9-4084-4165-b67f-14d7e8dd20b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAverageFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestRateDerivativesAbstract_308d3664-8634-4fe1-8e5d-12aa3bb3f0df" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_a1ab99b9-4084-4165-b67f-14d7e8dd20b5" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesNetUnrealizedGainLossRecognizedinAOCIDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesNetUnrealizedGainLossRecognizedinAOCIDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesNetUnrealizedGainLossRecognizedinAOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_5695e6d3-7d1a-449c-9caa-54d6818715de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_324fc388-54a3-4c4b-8c59-c8bc55d9e88a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_5695e6d3-7d1a-449c-9caa-54d6818715de" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_324fc388-54a3-4c4b-8c59-c8bc55d9e88a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_536e5a52-e00f-4ff5-b996-823b46e8c808" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_324fc388-54a3-4c4b-8c59-c8bc55d9e88a" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_536e5a52-e00f-4ff5-b996-823b46e8c808" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_536e5a52-e00f-4ff5-b996-823b46e8c808_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_536e5a52-e00f-4ff5-b996-823b46e8c808" xlink:to="loc_us-gaap_EquityComponentDomain_536e5a52-e00f-4ff5-b996-823b46e8c808_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_4ca8d047-6243-470c-b7de-4b8ea9cf22f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_536e5a52-e00f-4ff5-b996-823b46e8c808" xlink:to="loc_us-gaap_EquityComponentDomain_4ca8d047-6243-470c-b7de-4b8ea9cf22f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember_6183728a-d431-4b8c-acce-4500583601cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4ca8d047-6243-470c-b7de-4b8ea9cf22f4" xlink:to="loc_us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember_6183728a-d431-4b8c-acce-4500583601cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_718aee8c-1a4e-46dc-859a-ac200276658a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_324fc388-54a3-4c4b-8c59-c8bc55d9e88a" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_718aee8c-1a4e-46dc-859a-ac200276658a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_718aee8c-1a4e-46dc-859a-ac200276658a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_718aee8c-1a4e-46dc-859a-ac200276658a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_718aee8c-1a4e-46dc-859a-ac200276658a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_c8073c08-19e7-453e-99fc-89247c2cdf82" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_718aee8c-1a4e-46dc-859a-ac200276658a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_c8073c08-19e7-453e-99fc-89247c2cdf82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InterestRateSwapsTerminatedMember_7b85e5a6-12a7-4c0d-88bb-68f610ee651c" xlink:href="pagp-20231231.xsd#pagp_InterestRateSwapsTerminatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_c8073c08-19e7-453e-99fc-89247c2cdf82" xlink:to="loc_pagp_InterestRateSwapsTerminatedMember_7b85e5a6-12a7-4c0d-88bb-68f610ee651c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_282c9823-0362-4b62-aea8-06ab33155b18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_c8073c08-19e7-453e-99fc-89247c2cdf82" xlink:to="loc_us-gaap_InterestRateContractMember_282c9823-0362-4b62-aea8-06ab33155b18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_3e0e5be4-ca3d-446c-a1a7-8cfc9bc5a333" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_324fc388-54a3-4c4b-8c59-c8bc55d9e88a" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_3e0e5be4-ca3d-446c-a1a7-8cfc9bc5a333" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_3e0e5be4-ca3d-446c-a1a7-8cfc9bc5a333_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_3e0e5be4-ca3d-446c-a1a7-8cfc9bc5a333" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_3e0e5be4-ca3d-446c-a1a7-8cfc9bc5a333_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_d23b5295-deca-4d88-94aa-b663d92020a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_3e0e5be4-ca3d-446c-a1a7-8cfc9bc5a333" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_d23b5295-deca-4d88-94aa-b663d92020a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_2b681467-634a-41dd-b75d-b5a8cd0c0679" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_d23b5295-deca-4d88-94aa-b663d92020a3" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_2b681467-634a-41dd-b75d-b5a8cd0c0679" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_d786c71e-eb1f-474f-9f95-393225585c08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_d23b5295-deca-4d88-94aa-b663d92020a3" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_d786c71e-eb1f-474f-9f95-393225585c08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_cc127087-73ba-49ce-8092-a6c96d2fc623" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_324fc388-54a3-4c4b-8c59-c8bc55d9e88a" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_cc127087-73ba-49ce-8092-a6c96d2fc623" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_cc127087-73ba-49ce-8092-a6c96d2fc623_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_cc127087-73ba-49ce-8092-a6c96d2fc623" xlink:to="loc_us-gaap_HedgingRelationshipDomain_cc127087-73ba-49ce-8092-a6c96d2fc623_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_354390e2-8f17-4850-8765-5265bb0ac9e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_cc127087-73ba-49ce-8092-a6c96d2fc623" xlink:to="loc_us-gaap_HedgingRelationshipDomain_354390e2-8f17-4850-8765-5265bb0ac9e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_21b4725f-3707-44b7-857a-11b0e4a2f325" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_354390e2-8f17-4850-8765-5265bb0ac9e2" xlink:to="loc_us-gaap_CashFlowHedgingMember_21b4725f-3707-44b7-857a-11b0e4a2f325" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_6a0f285f-c17e-413d-a66b-7b0df26dc05e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_5695e6d3-7d1a-449c-9caa-54d6818715de" xlink:to="loc_us-gaap_DerivativeNotionalAmount_6a0f285f-c17e-413d-a66b-7b0df26dc05e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NetCashPaidReceivedforTerminatedHedgingInstruments_76833b78-c035-4b94-8185-4d896d9e4392" xlink:href="pagp-20231231.xsd#pagp_NetCashPaidReceivedforTerminatedHedgingInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_5695e6d3-7d1a-449c-9caa-54d6818715de" xlink:to="loc_pagp_NetCashPaidReceivedforTerminatedHedgingInstruments_76833b78-c035-4b94-8185-4d896d9e4392" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_9ef9d6d0-003d-4118-9f08-99b206f8f40c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_5695e6d3-7d1a-449c-9caa-54d6818715de" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_9ef9d6d0-003d-4118-9f08-99b206f8f40c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_fd223733-bd60-4726-83d9-bb39dcd90db3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_5695e6d3-7d1a-449c-9caa-54d6818715de" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_fd223733-bd60-4726-83d9-bb39dcd90db3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeDerivativeAtFairValueNet_321a82a7-b73f-452a-b69c-99312cb3b4a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateCashFlowHedgeDerivativeAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_5695e6d3-7d1a-449c-9caa-54d6818715de" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeDerivativeAtFairValueNet_321a82a7-b73f-452a-b69c-99312cb3b4a0" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesPreferredDistributionRateDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesPreferredDistributionRateDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesPreferredDistributionRateDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_0903802c-d9b3-419e-b50f-b98d489c954c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_a9f35cdf-f9cf-4227-bb86-0b93e1f4a140" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_0903802c-d9b3-419e-b50f-b98d489c954c" xlink:to="loc_us-gaap_DerivativeTable_a9f35cdf-f9cf-4227-bb86-0b93e1f4a140" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_65dc8502-68ee-48c4-9b9b-b43d280c316e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_a9f35cdf-f9cf-4227-bb86-0b93e1f4a140" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_65dc8502-68ee-48c4-9b9b-b43d280c316e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_65dc8502-68ee-48c4-9b9b-b43d280c316e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_65dc8502-68ee-48c4-9b9b-b43d280c316e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_65dc8502-68ee-48c4-9b9b-b43d280c316e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ac0910d7-ae68-4c61-a9f3-1e80a0a778d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_65dc8502-68ee-48c4-9b9b-b43d280c316e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ac0910d7-ae68-4c61-a9f3-1e80a0a778d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_0410517d-ccb3-4e82-8c53-551c8d19aeb5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmbeddedDerivativeFinancialInstrumentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_ac0910d7-ae68-4c61-a9f3-1e80a0a778d0" xlink:to="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_0410517d-ccb3-4e82-8c53-551c8d19aeb5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_70de50dd-61ca-43ef-ab7d-24da3b27a23d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_a9f35cdf-f9cf-4227-bb86-0b93e1f4a140" xlink:to="loc_us-gaap_HedgingDesignationAxis_70de50dd-61ca-43ef-ab7d-24da3b27a23d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_70de50dd-61ca-43ef-ab7d-24da3b27a23d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_70de50dd-61ca-43ef-ab7d-24da3b27a23d" xlink:to="loc_us-gaap_HedgingDesignationDomain_70de50dd-61ca-43ef-ab7d-24da3b27a23d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_889c8bca-59f1-4e91-9d8f-b3add4a57d69" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_70de50dd-61ca-43ef-ab7d-24da3b27a23d" xlink:to="loc_us-gaap_HedgingDesignationDomain_889c8bca-59f1-4e91-9d8f-b3add4a57d69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_d2d6697f-3372-440f-832e-0af45d02bf1b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_889c8bca-59f1-4e91-9d8f-b3add4a57d69" xlink:to="loc_us-gaap_NondesignatedMember_d2d6697f-3372-440f-832e-0af45d02bf1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_58c5b074-fe14-4a55-b9d1-738b3c3f5895" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_a9f35cdf-f9cf-4227-bb86-0b93e1f4a140" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_58c5b074-fe14-4a55-b9d1-738b3c3f5895" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_58c5b074-fe14-4a55-b9d1-738b3c3f5895_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_58c5b074-fe14-4a55-b9d1-738b3c3f5895" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_58c5b074-fe14-4a55-b9d1-738b3c3f5895_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_e0166d86-aacf-4253-bc98-d1f71d3365d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_58c5b074-fe14-4a55-b9d1-738b3c3f5895" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_e0166d86-aacf-4253-bc98-d1f71d3365d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseMember_903a5953-29c5-4610-96d7-df2134c5b7dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_e0166d86-aacf-4253-bc98-d1f71d3365d6" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseMember_903a5953-29c5-4610-96d7-df2134c5b7dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_90b2d268-0001-46c6-a4f9-c45443ad3156" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_0903802c-d9b3-419e-b50f-b98d489c954c" xlink:to="loc_us-gaap_DerivativeLiabilities_90b2d268-0001-46c6-a4f9-c45443ad3156" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration_998cabca-2a61-4904-9881-1733b1d3067b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilities_90b2d268-0001-46c6-a4f9-c45443ad3156" xlink:to="loc_us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration_998cabca-2a61-4904-9881-1733b1d3067b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet_1282e2c6-c343-4993-9cf4-9463a5cc564b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_0903802c-d9b3-419e-b50f-b98d489c954c" xlink:to="loc_us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet_1282e2c6-c343-4993-9cf4-9463a5cc564b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesFairValueDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#DerivativesandRiskManagementActivitiesFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/DerivativesandRiskManagementActivitiesFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bdc14f7d-7f67-4dcf-a3f4-6d24e524ebe2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_524ff53a-e58b-4b7e-ab38-08f18cd7b7c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bdc14f7d-7f67-4dcf-a3f4-6d24e524ebe2" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_524ff53a-e58b-4b7e-ab38-08f18cd7b7c3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_bd7ad746-b7de-4ca9-a96e-f8f828bc578c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_524ff53a-e58b-4b7e-ab38-08f18cd7b7c3" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_bd7ad746-b7de-4ca9-a96e-f8f828bc578c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_bd7ad746-b7de-4ca9-a96e-f8f828bc578c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_bd7ad746-b7de-4ca9-a96e-f8f828bc578c" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_bd7ad746-b7de-4ca9-a96e-f8f828bc578c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_ccf4d8e5-229e-4535-a9d9-e4b147216a51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_bd7ad746-b7de-4ca9-a96e-f8f828bc578c" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_ccf4d8e5-229e-4535-a9d9-e4b147216a51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_0a38c9b5-e9f5-4bdc-a3bc-135c35438292" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_ccf4d8e5-229e-4535-a9d9-e4b147216a51" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_0a38c9b5-e9f5-4bdc-a3bc-135c35438292" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4ab802da-897c-4906-abc4-4acff0302d51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_524ff53a-e58b-4b7e-ab38-08f18cd7b7c3" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4ab802da-897c-4906-abc4-4acff0302d51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_4ab802da-897c-4906-abc4-4acff0302d51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4ab802da-897c-4906-abc4-4acff0302d51" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_4ab802da-897c-4906-abc4-4acff0302d51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6cf80802-1c7c-497f-beae-1660bfa5349a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4ab802da-897c-4906-abc4-4acff0302d51" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6cf80802-1c7c-497f-beae-1660bfa5349a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_25809072-94d4-4f1f-92a2-7726da981d1b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6cf80802-1c7c-497f-beae-1660bfa5349a" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_25809072-94d4-4f1f-92a2-7726da981d1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_9c82eee0-35de-4e1f-920b-f49a0038e0e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6cf80802-1c7c-497f-beae-1660bfa5349a" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_9c82eee0-35de-4e1f-920b-f49a0038e0e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_d49170bc-77dc-4b94-8795-648b26a52519" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6cf80802-1c7c-497f-beae-1660bfa5349a" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_d49170bc-77dc-4b94-8795-648b26a52519" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_d4efbf4d-3174-4545-b9f0-9a56bd9d1963" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_524ff53a-e58b-4b7e-ab38-08f18cd7b7c3" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_d4efbf4d-3174-4545-b9f0-9a56bd9d1963" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_d4efbf4d-3174-4545-b9f0-9a56bd9d1963_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d4efbf4d-3174-4545-b9f0-9a56bd9d1963" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_d4efbf4d-3174-4545-b9f0-9a56bd9d1963_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_597b0725-af3a-4a84-b404-f3494d1b8458" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d4efbf4d-3174-4545-b9f0-9a56bd9d1963" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_597b0725-af3a-4a84-b404-f3494d1b8458" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_3bd55216-c87c-4a4b-8cbe-a478b60e738d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_597b0725-af3a-4a84-b404-f3494d1b8458" xlink:to="loc_us-gaap_CommodityContractMember_3bd55216-c87c-4a4b-8cbe-a478b60e738d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_c370df83-7ae1-4bd3-80c6-31326a8cbb1e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_597b0725-af3a-4a84-b404-f3494d1b8458" xlink:to="loc_us-gaap_InterestRateContractMember_c370df83-7ae1-4bd3-80c6-31326a8cbb1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_b7eef209-155d-4562-944f-9a61e3bff1a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmbeddedDerivativeFinancialInstrumentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_597b0725-af3a-4a84-b404-f3494d1b8458" xlink:to="loc_us-gaap_EmbeddedDerivativeFinancialInstrumentsMember_b7eef209-155d-4562-944f-9a61e3bff1a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_b9d085ae-e8cb-4157-86d2-3837bafec6f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bdc14f7d-7f67-4dcf-a3f4-6d24e524ebe2" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_b9d085ae-e8cb-4157-86d2-3837bafec6f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_1f6b0ec1-e7fd-47b2-a14b-dee76b37fb5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bdc14f7d-7f67-4dcf-a3f4-6d24e524ebe2" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_1f6b0ec1-e7fd-47b2-a14b-dee76b37fb5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_51a9a1f0-e0ff-482e-bfde-6cf56bb0d8a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_1f6b0ec1-e7fd-47b2-a14b-dee76b37fb5c" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_51a9a1f0-e0ff-482e-bfde-6cf56bb0d8a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_861b04e3-8747-4c62-9e33-5e67da40fc58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_1f6b0ec1-e7fd-47b2-a14b-dee76b37fb5c" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_861b04e3-8747-4c62-9e33-5e67da40fc58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityRecurringBasisStillHeldUnrealizedGainLossStatementOfIncomeExtensibleList_7ca2f3dd-a900-4025-be05-2a610df77204" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityRecurringBasisStillHeldUnrealizedGainLossStatementOfIncomeExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_861b04e3-8747-4c62-9e33-5e67da40fc58" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityRecurringBasisStillHeldUnrealizedGainLossStatementOfIncomeExtensibleList_7ca2f3dd-a900-4025-be05-2a610df77204" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements_bc3e1109-ba75-494e-b9c3-462a4218f235" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_1f6b0ec1-e7fd-47b2-a14b-dee76b37fb5c" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements_bc3e1109-ba75-494e-b9c3-462a4218f235" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_79cfc059-1b55-44da-8222-ecee434bf347" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_211cb87f-9f78-44f9-82e2-da6043241260" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bdc14f7d-7f67-4dcf-a3f4-6d24e524ebe2" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_211cb87f-9f78-44f9-82e2-da6043241260" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueRecurringBasisUnobservableInputReconciliationNetDerivativeAssetLiabilityGainLossStatementOfIncomeExtensibleList_3a6e8d17-09a5-4f25-89dc-9d1773eebb8e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueRecurringBasisUnobservableInputReconciliationNetDerivativeAssetLiabilityGainLossStatementOfIncomeExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_211cb87f-9f78-44f9-82e2-da6043241260" xlink:to="loc_us-gaap_FairValueRecurringBasisUnobservableInputReconciliationNetDerivativeAssetLiabilityGainLossStatementOfIncomeExtensibleList_3a6e8d17-09a5-4f25-89dc-9d1773eebb8e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_f22f5c9a-43cd-4be8-93c3-6dae0706f270" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_2ac16e1f-c915-4662-85af-7d0f58bdc37e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_f22f5c9a-43cd-4be8-93c3-6dae0706f270" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_2ac16e1f-c915-4662-85af-7d0f58bdc37e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0ffc03fb-fed1-4bac-b8db-401f86782af7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_2ac16e1f-c915-4662-85af-7d0f58bdc37e" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0ffc03fb-fed1-4bac-b8db-401f86782af7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_0ffc03fb-fed1-4bac-b8db-401f86782af7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0ffc03fb-fed1-4bac-b8db-401f86782af7" xlink:to="loc_us-gaap_RelatedPartyDomain_0ffc03fb-fed1-4bac-b8db-401f86782af7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_a19f97ef-7212-4d81-913d-914d05b4d2bc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0ffc03fb-fed1-4bac-b8db-401f86782af7" xlink:to="loc_us-gaap_RelatedPartyDomain_a19f97ef-7212-4d81-913d-914d05b4d2bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvesteeMember_31b121e1-fde8-4db1-87ca-f91a5469a1f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvesteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_a19f97ef-7212-4d81-913d-914d05b4d2bc" xlink:to="loc_us-gaap_EquityMethodInvesteeMember_31b121e1-fde8-4db1-87ca-f91a5469a1f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_a063c5da-c227-4422-b2de-2762fccba6b2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_2ac16e1f-c915-4662-85af-7d0f58bdc37e" xlink:to="loc_us-gaap_OtherCommitmentsAxis_a063c5da-c227-4422-b2de-2762fccba6b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_a063c5da-c227-4422-b2de-2762fccba6b2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_a063c5da-c227-4422-b2de-2762fccba6b2" xlink:to="loc_us-gaap_OtherCommitmentsDomain_a063c5da-c227-4422-b2de-2762fccba6b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_ab880c43-bade-496e-b931-c5b47b5ee641" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_a063c5da-c227-4422-b2de-2762fccba6b2" xlink:to="loc_us-gaap_OtherCommitmentsDomain_ab880c43-bade-496e-b931-c5b47b5ee641" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember_580a7e69-951f-41ce-90cb-217af00f0ba4" xlink:href="pagp-20231231.xsd#pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_ab880c43-bade-496e-b931-c5b47b5ee641" xlink:to="loc_pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember_580a7e69-951f-41ce-90cb-217af00f0ba4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ac7e778b-9ee4-49c2-ad8b-ceec5bb7eadf" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_2ac16e1f-c915-4662-85af-7d0f58bdc37e" xlink:to="loc_srt_RangeAxis_ac7e778b-9ee4-49c2-ad8b-ceec5bb7eadf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ac7e778b-9ee4-49c2-ad8b-ceec5bb7eadf_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ac7e778b-9ee4-49c2-ad8b-ceec5bb7eadf" xlink:to="loc_srt_RangeMember_ac7e778b-9ee4-49c2-ad8b-ceec5bb7eadf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7786e148-3509-466d-9654-6c63b2b801e7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ac7e778b-9ee4-49c2-ad8b-ceec5bb7eadf" xlink:to="loc_srt_RangeMember_7786e148-3509-466d-9654-6c63b2b801e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_b84b3b2b-6c3a-4e64-9ad7-9454e59933d4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7786e148-3509-466d-9654-6c63b2b801e7" xlink:to="loc_srt_MinimumMember_b84b3b2b-6c3a-4e64-9ad7-9454e59933d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_e8ad9d64-9abb-4190-9205-9dd1aa78cea1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7786e148-3509-466d-9654-6c63b2b801e7" xlink:to="loc_srt_MaximumMember_e8ad9d64-9abb-4190-9205-9dd1aa78cea1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_27977d30-dbf4-4c7d-8349-da7fcd68b29b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_2ac16e1f-c915-4662-85af-7d0f58bdc37e" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_27977d30-dbf4-4c7d-8349-da7fcd68b29b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_27977d30-dbf4-4c7d-8349-da7fcd68b29b_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_27977d30-dbf4-4c7d-8349-da7fcd68b29b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_27977d30-dbf4-4c7d-8349-da7fcd68b29b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_4b771a1a-145c-4be7-b68a-a6e4e685138e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_27977d30-dbf4-4c7d-8349-da7fcd68b29b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_4b771a1a-145c-4be7-b68a-a6e4e685138e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember_895d7373-29db-40f7-888c-0846646d3dcd" xlink:href="pagp-20231231.xsd#pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_4b771a1a-145c-4be7-b68a-a6e4e685138e" xlink:to="loc_pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember_895d7373-29db-40f7-888c-0846646d3dcd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_e963c222-b6d9-4c83-b8de-86e6fe2eec0a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_f22f5c9a-43cd-4be8-93c3-6dae0706f270" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_e963c222-b6d9-4c83-b8de-86e6fe2eec0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LesseeLeasesTermOfContract_6f3b84c4-882d-4742-b1fe-5822a0e38e17" xlink:href="pagp-20231231.xsd#pagp_LesseeLeasesTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_f22f5c9a-43cd-4be8-93c3-6dae0706f270" xlink:to="loc_pagp_LesseeLeasesTermOfContract_6f3b84c4-882d-4742-b1fe-5822a0e38e17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LesseeLeasesRenewalTerm_64310271-1e5b-4327-b075-12bc8d17c9cd" xlink:href="pagp-20231231.xsd#pagp_LesseeLeasesRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_f22f5c9a-43cd-4be8-93c3-6dae0706f270" xlink:to="loc_pagp_LesseeLeasesRenewalTerm_64310271-1e5b-4327-b075-12bc8d17c9cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorLeaseDescriptionLineItems_b36b776e-acef-4c1f-9231-c9611c5d23c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorLeaseDescriptionTable_98b49941-0fb9-47df-9ff3-fb26cbc7c72c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_b36b776e-acef-4c1f-9231-c9611c5d23c1" xlink:to="loc_us-gaap_LessorLeaseDescriptionTable_98b49941-0fb9-47df-9ff3-fb26cbc7c72c" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_dec93682-2018-4a03-965f-26954d03eb00" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LessorLeaseDescriptionTable_98b49941-0fb9-47df-9ff3-fb26cbc7c72c" xlink:to="loc_srt_RangeAxis_dec93682-2018-4a03-965f-26954d03eb00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_dec93682-2018-4a03-965f-26954d03eb00_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f2aa6d27-d6c2-43a4-b688-feb5f8d5ad79" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_03202842-620e-402d-9009-3faaed27cf3d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_111429dd-b592-4e43-9f45-7cd12a99a0cb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeaseTermOfContract_b4179a25-8535-4968-939a-a0f1bf3bd754" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_b36b776e-acef-4c1f-9231-c9611c5d23c1" xlink:to="loc_us-gaap_LessorOperatingLeaseTermOfContract_b4179a25-8535-4968-939a-a0f1bf3bd754" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/LeasesAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#LeasesAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/LeasesAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_703ea294-5e9c-4d0e-9430-986d7b6a6342" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_703ea294-5e9c-4d0e-9430-986d7b6a6342" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d902835a-d474-4b2a-9765-94f6ab7e80f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_703ea294-5e9c-4d0e-9430-986d7b6a6342" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d902835a-d474-4b2a-9765-94f6ab7e80f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_d902835a-d474-4b2a-9765-94f6ab7e80f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d902835a-d474-4b2a-9765-94f6ab7e80f7" xlink:to="loc_us-gaap_RelatedPartyDomain_d902835a-d474-4b2a-9765-94f6ab7e80f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_21fdca9d-b361-47d0-88da-44aeafafb8b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d902835a-d474-4b2a-9765-94f6ab7e80f7" xlink:to="loc_us-gaap_RelatedPartyDomain_21fdca9d-b361-47d0-88da-44aeafafb8b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvesteeMember_b3eb8416-0cb0-4629-b77e-f681cad5d676" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvesteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_21fdca9d-b361-47d0-88da-44aeafafb8b5" xlink:to="loc_us-gaap_EquityMethodInvesteeMember_b3eb8416-0cb0-4629-b77e-f681cad5d676" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_b9fa8767-755a-4dc8-a3e5-a01d45dc0b8b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_703ea294-5e9c-4d0e-9430-986d7b6a6342" xlink:to="loc_us-gaap_OtherCommitmentsAxis_b9fa8767-755a-4dc8-a3e5-a01d45dc0b8b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_b9fa8767-755a-4dc8-a3e5-a01d45dc0b8b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_b9fa8767-755a-4dc8-a3e5-a01d45dc0b8b" xlink:to="loc_us-gaap_OtherCommitmentsDomain_b9fa8767-755a-4dc8-a3e5-a01d45dc0b8b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_5de88824-7492-4a4d-9bad-208e1e178a51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_b9fa8767-755a-4dc8-a3e5-a01d45dc0b8b" xlink:to="loc_us-gaap_OtherCommitmentsDomain_5de88824-7492-4a4d-9bad-208e1e178a51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember_0c5ff37e-bf97-471d-8fad-dbb4c74a4995" xlink:href="pagp-20231231.xsd#pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_5de88824-7492-4a4d-9bad-208e1e178a51" xlink:to="loc_pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember_0c5ff37e-bf97-471d-8fad-dbb4c74a4995" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_2326cdfb-ecf7-4964-a0ed-fa2dd6857aed" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_703ea294-5e9c-4d0e-9430-986d7b6a6342" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_2326cdfb-ecf7-4964-a0ed-fa2dd6857aed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_2326cdfb-ecf7-4964-a0ed-fa2dd6857aed_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_2326cdfb-ecf7-4964-a0ed-fa2dd6857aed" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_2326cdfb-ecf7-4964-a0ed-fa2dd6857aed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_6d562d2b-9166-4f35-9fb9-275d695d67bd" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_2326cdfb-ecf7-4964-a0ed-fa2dd6857aed" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_6d562d2b-9166-4f35-9fb9-275d695d67bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember_3d71091c-dc5e-4cd5-802c-ef4239b4fe59" xlink:href="pagp-20231231.xsd#pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_6d562d2b-9166-4f35-9fb9-275d695d67bd" xlink:to="loc_pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember_3d71091c-dc5e-4cd5-802c-ef4239b4fe59" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_8367bd80-c8f0-4f2d-bf39-d5c6f85e9dad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_8367bd80-c8f0-4f2d-bf39-d5c6f85e9dad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_96a4f79a-e033-4240-8989-e5aadd744bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_96a4f79a-e033-4240-8989-e5aadd744bdc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAccumulatedAmortization_9a7c54fe-a125-4410-adfa-8469753e7082" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseRightOfUseAssetAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAccumulatedAmortization_9a7c54fe-a125-4410-adfa-8469753e7082" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAsset_6894e4a9-976a-426f-9943-fd0d040abe90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAsset_6894e4a9-976a-426f-9943-fd0d040abe90" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList_7c8038e2-0361-4698-9d80-1a17570e8a21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAsset_6894e4a9-976a-426f-9943-fd0d040abe90" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList_7c8038e2-0361-4698-9d80-1a17570e8a21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LeasesRightOfUseAsset_00fea53e-845e-40a6-bd03-c2aea706304d" xlink:href="pagp-20231231.xsd#pagp_LeasesRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_pagp_LeasesRightOfUseAsset_00fea53e-845e-40a6-bd03-c2aea706304d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseDescriptionAbstract_a9b3f08d-12cc-4680-87bd-6d620ccc1420" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseDescriptionAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_us-gaap_LesseeOperatingLeaseDescriptionAbstract_a9b3f08d-12cc-4680-87bd-6d620ccc1420" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_d9a2f081-647a-42cf-ae9a-5b119e89dd04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeOperatingLeaseDescriptionAbstract_a9b3f08d-12cc-4680-87bd-6d620ccc1420" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_d9a2f081-647a-42cf-ae9a-5b119e89dd04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_085f6e94-7b9a-43de-a2c0-9cd692524c12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilityCurrent_d9a2f081-647a-42cf-ae9a-5b119e89dd04" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_085f6e94-7b9a-43de-a2c0-9cd692524c12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_e1d5ca5e-ef3f-46ff-96ac-53be78de1552" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeOperatingLeaseDescriptionAbstract_a9b3f08d-12cc-4680-87bd-6d620ccc1420" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_e1d5ca5e-ef3f-46ff-96ac-53be78de1552" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_f1813c9b-17ad-496a-8f41-de39fb202e9d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeOperatingLeaseDescriptionAbstract_a9b3f08d-12cc-4680-87bd-6d620ccc1420" xlink:to="loc_us-gaap_OperatingLeaseLiability_f1813c9b-17ad-496a-8f41-de39fb202e9d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeFinanceLeaseDescriptionAbstract_3ce7b03b-ac6c-4a17-a423-17116e33c206" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeFinanceLeaseDescriptionAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_us-gaap_LesseeFinanceLeaseDescriptionAbstract_3ce7b03b-ac6c-4a17-a423-17116e33c206" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_7059d9f7-8c9f-44bd-8f05-2028400bb13a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeFinanceLeaseDescriptionAbstract_3ce7b03b-ac6c-4a17-a423-17116e33c206" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_7059d9f7-8c9f-44bd-8f05-2028400bb13a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_e58a5718-dd0b-4110-854a-87bb29686241" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilityCurrent_7059d9f7-8c9f-44bd-8f05-2028400bb13a" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_e58a5718-dd0b-4110-854a-87bb29686241" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_da9f927b-5323-406a-92d3-d1525e48e8fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeFinanceLeaseDescriptionAbstract_3ce7b03b-ac6c-4a17-a423-17116e33c206" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_da9f927b-5323-406a-92d3-d1525e48e8fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_54e69ca9-412a-4e0a-aac4-758a9cfe5f52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_da9f927b-5323-406a-92d3-d1525e48e8fc" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_54e69ca9-412a-4e0a-aac4-758a9cfe5f52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_fc934f79-1abc-4df7-b543-85bab3249827" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeFinanceLeaseDescriptionAbstract_3ce7b03b-ac6c-4a17-a423-17116e33c206" xlink:to="loc_us-gaap_FinanceLeaseLiability_fc934f79-1abc-4df7-b543-85bab3249827" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LeasesLiability_6bc483da-55c0-43a7-9727-aa2f7fb52510" xlink:href="pagp-20231231.xsd#pagp_LeasesLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_pagp_LeasesLiability_6bc483da-55c0-43a7-9727-aa2f7fb52510" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_843f9d3a-389d-477d-b8d2-526a012e6b6c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9427585b-7b7e-4c7a-b01c-3c87a4db1cb3" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_843f9d3a-389d-477d-b8d2-526a012e6b6c" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/LeasesMaturityofLeaseLiabilitiesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#LeasesMaturityofLeaseLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/LeasesMaturityofLeaseLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f112cea-b680-4a33-9886-d7dc0279913e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_e854487e-0f7d-42e0-ae7b-e19f1c201be6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f112cea-b680-4a33-9886-d7dc0279913e" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_e854487e-0f7d-42e0-ae7b-e19f1c201be6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_ffe760e4-d3cb-4537-8426-9b43869723fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e854487e-0f7d-42e0-ae7b-e19f1c201be6" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_ffe760e4-d3cb-4537-8426-9b43869723fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_ffe760e4-d3cb-4537-8426-9b43869723fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_ffe760e4-d3cb-4537-8426-9b43869723fc" xlink:to="loc_us-gaap_RelatedPartyDomain_ffe760e4-d3cb-4537-8426-9b43869723fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_2ff4f556-ade5-4cd6-84d0-a7b1463e023b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_ffe760e4-d3cb-4537-8426-9b43869723fc" xlink:to="loc_us-gaap_RelatedPartyDomain_2ff4f556-ade5-4cd6-84d0-a7b1463e023b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvesteeMember_e99b8878-e87d-44e8-88fb-46c2d3f5cc3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvesteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_2ff4f556-ade5-4cd6-84d0-a7b1463e023b" xlink:to="loc_us-gaap_EquityMethodInvesteeMember_e99b8878-e87d-44e8-88fb-46c2d3f5cc3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_d8ca566d-db9a-4b14-a0dc-ff6b3872ece3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e854487e-0f7d-42e0-ae7b-e19f1c201be6" xlink:to="loc_us-gaap_OtherCommitmentsAxis_d8ca566d-db9a-4b14-a0dc-ff6b3872ece3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_d8ca566d-db9a-4b14-a0dc-ff6b3872ece3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_d8ca566d-db9a-4b14-a0dc-ff6b3872ece3" xlink:to="loc_us-gaap_OtherCommitmentsDomain_d8ca566d-db9a-4b14-a0dc-ff6b3872ece3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_99b5aa8b-a341-4286-962e-8c460ddc77d5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_d8ca566d-db9a-4b14-a0dc-ff6b3872ece3" xlink:to="loc_us-gaap_OtherCommitmentsDomain_99b5aa8b-a341-4286-962e-8c460ddc77d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember_f1ea01d1-887c-4634-aa6c-9a8dd8a8e413" xlink:href="pagp-20231231.xsd#pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_99b5aa8b-a341-4286-962e-8c460ddc77d5" xlink:to="loc_pagp_AgreementsToUtilizeAssetsOfEquityMethodInvesteeMember_f1ea01d1-887c-4634-aa6c-9a8dd8a8e413" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_d7701c16-5c5c-48b5-9e00-ea36a1f39089" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e854487e-0f7d-42e0-ae7b-e19f1c201be6" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_d7701c16-5c5c-48b5-9e00-ea36a1f39089" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_d7701c16-5c5c-48b5-9e00-ea36a1f39089_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_d7701c16-5c5c-48b5-9e00-ea36a1f39089" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_d7701c16-5c5c-48b5-9e00-ea36a1f39089_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_4237c12a-6363-45b3-89a3-51236e4aa11e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_d7701c16-5c5c-48b5-9e00-ea36a1f39089" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_4237c12a-6363-45b3-89a3-51236e4aa11e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember_fc388d79-6235-4273-a5cc-64b952284520" xlink:href="pagp-20231231.xsd#pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_4237c12a-6363-45b3-89a3-51236e4aa11e" xlink:to="loc_pagp_EquityMethodInvesteeThatOwnsLeasedStorageTanksMember_fc388d79-6235-4273-a5cc-64b952284520" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f112cea-b680-4a33-9886-d7dc0279913e" xlink:to="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_77f5acb0-fb9d-4559-82b2-a849e0ae97f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_77f5acb0-fb9d-4559-82b2-a849e0ae97f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_68b5a5fd-6e02-45f7-8c1d-85032c2766a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_68b5a5fd-6e02-45f7-8c1d-85032c2766a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_38fa4a22-65e8-40f6-a902-087626ceeaff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_38fa4a22-65e8-40f6-a902-087626ceeaff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_6faa58de-10aa-486c-b516-e2bf36e0b1e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_6faa58de-10aa-486c-b516-e2bf36e0b1e0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_d2087064-73bb-4e28-b226-e09155f6ad82" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_d2087064-73bb-4e28-b226-e09155f6ad82" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_8da2ded5-3cc4-4dfe-beb7-702ee8add893" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_8da2ded5-3cc4-4dfe-beb7-702ee8add893" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_b500f5c0-9832-4308-b8a3-c1c6e88dfa89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_b500f5c0-9832-4308-b8a3-c1c6e88dfa89" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_ae067f78-963c-4779-a45b-58f6939a87c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_ae067f78-963c-4779-a45b-58f6939a87c6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_d4767826-5f5c-4c25-86fd-60dedf17f3b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_9277e00c-cd63-45ab-ba1c-86791585fa0e" xlink:to="loc_us-gaap_OperatingLeaseLiability_d4767826-5f5c-4c25-86fd-60dedf17f3b0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_6f112cea-b680-4a33-9886-d7dc0279913e" xlink:to="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_4d5c1723-8984-4ebc-a6ab-f569fad3968c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_4d5c1723-8984-4ebc-a6ab-f569fad3968c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_c6a21bf2-000d-48f7-a802-29df59cde280" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_c6a21bf2-000d-48f7-a802-29df59cde280" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_2ed36b25-9bed-4871-9b0d-4d91517d0a10" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_2ed36b25-9bed-4871-9b0d-4d91517d0a10" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_285df8f2-c0e6-4664-b2ab-ecc793707421" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_285df8f2-c0e6-4664-b2ab-ecc793707421" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_b87e5c79-90a2-47ea-a294-d6697c07feab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_b87e5c79-90a2-47ea-a294-d6697c07feab" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_8a0504e7-32cb-4c3e-b12c-b953b16abec3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_8a0504e7-32cb-4c3e-b12c-b953b16abec3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_f16f37ee-cc9b-47c1-9f89-40d310b3fee1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_f16f37ee-cc9b-47c1-9f89-40d310b3fee1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_b5f0c632-0058-44d1-bbc4-c703decbbbc4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_b5f0c632-0058-44d1-bbc4-c703decbbbc4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_58a7788a-6818-47c0-a70b-9922453659a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_FinanceLeaseLiability_58a7788a-6818-47c0-a70b-9922453659a0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_b4e264ad-f805-477e-82bc-a5a0cce42754" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_18d1466a-cd14-45f6-a7f9-b0549e570e11" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_b4e264ad-f805-477e-82bc-a5a0cce42754" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/LeasesLessorOperatingLeaseRevenueDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#LeasesLessorOperatingLeaseRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/LeasesLessorOperatingLeaseRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorLeaseDescriptionLineItems_be7ae3fd-014c-49aa-a772-d21f28e8cefb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorLeaseDescriptionTable_5540f49d-6006-4961-a6b7-8fb9867ec4fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_be7ae3fd-014c-49aa-a772-d21f28e8cefb" xlink:to="loc_us-gaap_LessorLeaseDescriptionTable_5540f49d-6006-4961-a6b7-8fb9867ec4fc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_0dc2cc47-83f3-4e58-bd1b-f560ff2fe5ee" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LessorLeaseDescriptionTable_5540f49d-6006-4961-a6b7-8fb9867ec4fc" xlink:to="loc_srt_ProductOrServiceAxis_0dc2cc47-83f3-4e58-bd1b-f560ff2fe5ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_0dc2cc47-83f3-4e58-bd1b-f560ff2fe5ee_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_0dc2cc47-83f3-4e58-bd1b-f560ff2fe5ee" xlink:to="loc_srt_ProductsAndServicesDomain_0dc2cc47-83f3-4e58-bd1b-f560ff2fe5ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_4fd111b7-4366-48cd-83df-d79428406b54" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_0dc2cc47-83f3-4e58-bd1b-f560ff2fe5ee" xlink:to="loc_srt_ProductsAndServicesDomain_4fd111b7-4366-48cd-83df-d79428406b54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_7df4717f-9522-4fea-8159-d97ec3b97eae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_4fd111b7-4366-48cd-83df-d79428406b54" xlink:to="loc_us-gaap_ServiceMember_7df4717f-9522-4fea-8159-d97ec3b97eae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseIncome_f075d882-c007-40c0-9ed9-5d220719d69c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLeaseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LessorLeaseDescriptionLineItems_be7ae3fd-014c-49aa-a772-d21f28e8cefb" xlink:to="loc_us-gaap_OperatingLeaseLeaseIncome_f075d882-c007-40c0-9ed9-5d220719d69c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseIncomeComprehensiveIncomeExtensibleList_fa47ac68-8679-458c-8395-48ad1c3cd8ed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseIncomeComprehensiveIncomeExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeaseLeaseIncome_f075d882-c007-40c0-9ed9-5d220719d69c" xlink:to="loc_us-gaap_OperatingLeaseIncomeComprehensiveIncomeExtensibleList_fa47ac68-8679-458c-8395-48ad1c3cd8ed" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/IncomeTaxesDeferredTaxAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#IncomeTaxesDeferredTaxAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/IncomeTaxesDeferredTaxAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_093a78e0-9e16-453b-85fc-183f51d9e0d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_b2e4f454-e84b-4a57-a745-9810fb9ae367" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_093a78e0-9e16-453b-85fc-183f51d9e0d0" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_b2e4f454-e84b-4a57-a745-9810fb9ae367" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_1b005918-53a4-445c-8029-8fbd5edcb317" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_b2e4f454-e84b-4a57-a745-9810fb9ae367" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_1b005918-53a4-445c-8029-8fbd5edcb317" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_1b005918-53a4-445c-8029-8fbd5edcb317_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_1b005918-53a4-445c-8029-8fbd5edcb317" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_1b005918-53a4-445c-8029-8fbd5edcb317_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_b25cdbab-7d8b-4630-98c5-523e1489a620" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_1b005918-53a4-445c-8029-8fbd5edcb317" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_b25cdbab-7d8b-4630-98c5-523e1489a620" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_46e4f8c5-74f3-4038-9e93-a7417ed18c02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_b25cdbab-7d8b-4630-98c5-523e1489a620" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_46e4f8c5-74f3-4038-9e93-a7417ed18c02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_39531248-7c08-4f38-9a6b-5b1cec3bc0e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_b25cdbab-7d8b-4630-98c5-523e1489a620" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_39531248-7c08-4f38-9a6b-5b1cec3bc0e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_414504e2-d56a-47bd-b07b-a2e1c725ce64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComponentsOfDeferredTaxAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_093a78e0-9e16-453b-85fc-183f51d9e0d0" xlink:to="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_414504e2-d56a-47bd-b07b-a2e1c725ce64" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DeferredTaxAssetsInvestmentsInSubsidiaries_96545899-3679-48a7-8b3d-565a62f1ddde" xlink:href="pagp-20231231.xsd#pagp_DeferredTaxAssetsInvestmentsInSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_414504e2-d56a-47bd-b07b-a2e1c725ce64" xlink:to="loc_pagp_DeferredTaxAssetsInvestmentsInSubsidiaries_96545899-3679-48a7-8b3d-565a62f1ddde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_dd868f1c-6f35-4a5e-be16-de9e91e518d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_414504e2-d56a-47bd-b07b-a2e1c725ce64" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_dd868f1c-6f35-4a5e-be16-de9e91e518d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DeferredTaxAssetsLeasingArrangements_ad822f72-aece-418a-9ee4-689f8b750d27" xlink:href="pagp-20231231.xsd#pagp_DeferredTaxAssetsLeasingArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_414504e2-d56a-47bd-b07b-a2e1c725ce64" xlink:to="loc_pagp_DeferredTaxAssetsLeasingArrangements_ad822f72-aece-418a-9ee4-689f8b750d27" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOther_ebf2d2e8-a332-4153-89da-794251e89351" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_414504e2-d56a-47bd-b07b-a2e1c725ce64" xlink:to="loc_us-gaap_DeferredTaxAssetsOther_ebf2d2e8-a332-4153-89da-794251e89351" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_0ff72170-dfe3-493c-a71e-3a79d6b7bb08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_414504e2-d56a-47bd-b07b-a2e1c725ce64" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_0ff72170-dfe3-493c-a71e-3a79d6b7bb08" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_a09afa83-7c22-4ede-80c6-29a1d21423d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_093a78e0-9e16-453b-85fc-183f51d9e0d0" xlink:to="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_a09afa83-7c22-4ede-80c6-29a1d21423d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_85bdbad8-0011-4a2a-9c41-29161af351b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_a09afa83-7c22-4ede-80c6-29a1d21423d0" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_85bdbad8-0011-4a2a-9c41-29161af351b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesDerivatives_d7dd90c3-b13d-4ed9-8f79-410e5af9f35a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_a09afa83-7c22-4ede-80c6-29a1d21423d0" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesDerivatives_d7dd90c3-b13d-4ed9-8f79-410e5af9f35a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesLeasingArrangements_0fbf2b69-3612-4bf3-91cf-3606ac0240c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesLeasingArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_a09afa83-7c22-4ede-80c6-29a1d21423d0" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesLeasingArrangements_0fbf2b69-3612-4bf3-91cf-3606ac0240c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesOther_d942177f-a25e-4c8f-b773-42374f3127c5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_a09afa83-7c22-4ede-80c6-29a1d21423d0" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesOther_d942177f-a25e-4c8f-b773-42374f3127c5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_64853179-d7a1-490e-87a5-6a7f8ad89854" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_a09afa83-7c22-4ede-80c6-29a1d21423d0" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilities_64853179-d7a1-490e-87a5-6a7f8ad89854" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_7db03ec4-c7b7-4814-bb3f-3874fca0843d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_093a78e0-9e16-453b-85fc-183f51d9e0d0" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_7db03ec4-c7b7-4814-bb3f-3874fca0843d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_6d0846aa-d3f5-4c81-862f-b39448469559" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_093a78e0-9e16-453b-85fc-183f51d9e0d0" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_6d0846aa-d3f5-4c81-862f-b39448469559" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_bfc083c5-5b44-4aa1-93e0-e10afca82739" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_093a78e0-9e16-453b-85fc-183f51d9e0d0" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_bfc083c5-5b44-4aa1-93e0-e10afca82739" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationLineItems_4cb1ed88-93dd-452d-b74b-d0a57be7f05d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExaminationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationTable_8fcf4554-1c73-4a4c-a04f-d52adb48c997" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExaminationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_4cb1ed88-93dd-452d-b74b-d0a57be7f05d" xlink:to="loc_us-gaap_IncomeTaxExaminationTable_8fcf4554-1c73-4a4c-a04f-d52adb48c997" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameAxis_8e007457-33db-442f-b89c-6ac10e2e3319" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_8fcf4554-1c73-4a4c-a04f-d52adb48c997" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameAxis_8e007457-33db-442f-b89c-6ac10e2e3319" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_8e007457-33db-442f-b89c-6ac10e2e3319_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_8e007457-33db-442f-b89c-6ac10e2e3319" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_8e007457-33db-442f-b89c-6ac10e2e3319_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_fb804045-4ef2-45ef-81a7-76a339255559" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_8e007457-33db-442f-b89c-6ac10e2e3319" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_fb804045-4ef2-45ef-81a7-76a339255559" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CanadianTaxAuthoritiesMember_eedc1dd0-95b0-4dda-b90e-f5e1bcf1d74e" xlink:href="pagp-20231231.xsd#pagp_CanadianTaxAuthoritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_fb804045-4ef2-45ef-81a7-76a339255559" xlink:to="loc_pagp_CanadianTaxAuthoritiesMember_eedc1dd0-95b0-4dda-b90e-f5e1bcf1d74e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_1560b6cf-fd48-47c0-b43b-24537b3fbca7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_8fcf4554-1c73-4a4c-a04f-d52adb48c997" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_1560b6cf-fd48-47c0-b43b-24537b3fbca7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_1560b6cf-fd48-47c0-b43b-24537b3fbca7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_1560b6cf-fd48-47c0-b43b-24537b3fbca7" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_1560b6cf-fd48-47c0-b43b-24537b3fbca7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_025eba72-3eb5-4f23-bb1f-1fa0f969c8d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_1560b6cf-fd48-47c0-b43b-24537b3fbca7" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_025eba72-3eb5-4f23-bb1f-1fa0f969c8d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_a2823d4a-f694-44b1-b108-797d279978f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_025eba72-3eb5-4f23-bb1f-1fa0f969c8d7" xlink:to="loc_us-gaap_DomesticCountryMember_a2823d4a-f694-44b1-b108-797d279978f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_b5aa6add-aea3-40aa-9b8b-caa49532bcf2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_025eba72-3eb5-4f23-bb1f-1fa0f969c8d7" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_b5aa6add-aea3-40aa-9b8b-caa49532bcf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_2c8dee1f-4eab-4941-b308-1fbde146cb76" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_025eba72-3eb5-4f23-bb1f-1fa0f969c8d7" xlink:to="loc_us-gaap_ForeignCountryMember_2c8dee1f-4eab-4941-b308-1fbde146cb76" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_64c53a49-5f43-4896-bc5f-7609b712b968" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_8fcf4554-1c73-4a4c-a04f-d52adb48c997" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_64c53a49-5f43-4896-bc5f-7609b712b968" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_64c53a49-5f43-4896-bc5f-7609b712b968_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_64c53a49-5f43-4896-bc5f-7609b712b968" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_64c53a49-5f43-4896-bc5f-7609b712b968_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_a5efe3e2-297f-4822-a122-86899c058a53" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_64c53a49-5f43-4896-bc5f-7609b712b968" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_a5efe3e2-297f-4822-a122-86899c058a53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_6949a3eb-ab46-40cd-a9c0-5750b664118a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_a5efe3e2-297f-4822-a122-86899c058a53" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_6949a3eb-ab46-40cd-a9c0-5750b664118a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_08220631-8510-4ded-bb80-8abb618e059f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_4cb1ed88-93dd-452d-b74b-d0a57be7f05d" xlink:to="loc_us-gaap_OperatingLossCarryforwards_08220631-8510-4ded-bb80-8abb618e059f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IncomeTaxExaminationAmountofAssessmentDisputed_2d169c54-e7ae-462b-ae48-a60bbe9bdc7a" xlink:href="pagp-20231231.xsd#pagp_IncomeTaxExaminationAmountofAssessmentDisputed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_4cb1ed88-93dd-452d-b74b-d0a57be7f05d" xlink:to="loc_pagp_IncomeTaxExaminationAmountofAssessmentDisputed_2d169c54-e7ae-462b-ae48-a60bbe9bdc7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IncomeTaxExaminationAmountofDisputedAssessmentPaid_c972bf27-936a-4882-b94f-b6e57bc926c6" xlink:href="pagp-20231231.xsd#pagp_IncomeTaxExaminationAmountofDisputedAssessmentPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_4cb1ed88-93dd-452d-b74b-d0a57be7f05d" xlink:to="loc_pagp_IncomeTaxExaminationAmountofDisputedAssessmentPaid_c972bf27-936a-4882-b94f-b6e57bc926c6" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/MajorCustomersandConcentrationofCreditRiskDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#MajorCustomersandConcentrationofCreditRiskDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/MajorCustomersandConcentrationofCreditRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_96281d78-d368-467e-868b-cb166c276b4f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_e409e557-b8c1-4968-b8e5-421df50f53b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_96281d78-d368-467e-868b-cb166c276b4f" xlink:to="loc_us-gaap_ConcentrationRiskTable_e409e557-b8c1-4968-b8e5-421df50f53b4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_d0a480c2-6d1e-4234-8000-24766a0bf7cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_e409e557-b8c1-4968-b8e5-421df50f53b4" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_d0a480c2-6d1e-4234-8000-24766a0bf7cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_d0a480c2-6d1e-4234-8000-24766a0bf7cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_d0a480c2-6d1e-4234-8000-24766a0bf7cb" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_d0a480c2-6d1e-4234-8000-24766a0bf7cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_579271d2-eead-470d-9f64-55922ee80fc1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_d0a480c2-6d1e-4234-8000-24766a0bf7cb" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_579271d2-eead-470d-9f64-55922ee80fc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_2ad5cc0c-cf1a-468f-b2ec-bfb98448c195" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_579271d2-eead-470d-9f64-55922ee80fc1" xlink:to="loc_us-gaap_SalesRevenueNetMember_2ad5cc0c-cf1a-468f-b2ec-bfb98448c195" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_5bcc1af0-fc0e-4340-9f68-54f5b4a9095e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_e409e557-b8c1-4968-b8e5-421df50f53b4" xlink:to="loc_srt_MajorCustomersAxis_5bcc1af0-fc0e-4340-9f68-54f5b4a9095e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_5bcc1af0-fc0e-4340-9f68-54f5b4a9095e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_5bcc1af0-fc0e-4340-9f68-54f5b4a9095e" xlink:to="loc_srt_NameOfMajorCustomerDomain_5bcc1af0-fc0e-4340-9f68-54f5b4a9095e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_7730af9c-2fe7-4098-b8a2-a2521c433840" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_5bcc1af0-fc0e-4340-9f68-54f5b4a9095e" xlink:to="loc_srt_NameOfMajorCustomerDomain_7730af9c-2fe7-4098-b8a2-a2521c433840" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ExxonMobilCorporationMember_7e8407b6-82c4-4c87-b279-0b7388149f15" xlink:href="pagp-20231231.xsd#pagp_ExxonMobilCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_7730af9c-2fe7-4098-b8a2-a2521c433840" xlink:to="loc_pagp_ExxonMobilCorporationMember_7e8407b6-82c4-4c87-b279-0b7388149f15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_MarathonPetroleumCorporationMember_7a8ea44d-b42a-4ad5-be84-ae527981cf61" xlink:href="pagp-20231231.xsd#pagp_MarathonPetroleumCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_7730af9c-2fe7-4098-b8a2-a2521c433840" xlink:to="loc_pagp_MarathonPetroleumCorporationMember_7a8ea44d-b42a-4ad5-be84-ae527981cf61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_BPPlcAndSubsidiariesMember_a2d6daee-eec3-47b4-9691-64dbe0d5032c" xlink:href="pagp-20231231.xsd#pagp_BPPlcAndSubsidiariesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_7730af9c-2fe7-4098-b8a2-a2521c433840" xlink:to="loc_pagp_BPPlcAndSubsidiariesMember_a2d6daee-eec3-47b4-9691-64dbe0d5032c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_e6c086a9-c447-4f23-a41e-0bedc0f45c5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_e409e557-b8c1-4968-b8e5-421df50f53b4" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_e6c086a9-c447-4f23-a41e-0bedc0f45c5a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_e6c086a9-c447-4f23-a41e-0bedc0f45c5a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_e6c086a9-c447-4f23-a41e-0bedc0f45c5a" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_e6c086a9-c447-4f23-a41e-0bedc0f45c5a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_21f8a977-0786-48ed-9450-4961fdf6fb18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_e6c086a9-c447-4f23-a41e-0bedc0f45c5a" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_21f8a977-0786-48ed-9450-4961fdf6fb18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_5100f22d-2e96-4331-b0fb-3f143f4d6494" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_21f8a977-0786-48ed-9450-4961fdf6fb18" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_5100f22d-2e96-4331-b0fb-3f143f4d6494" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_012e27f6-c685-4952-b7ac-926b7601af65" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_96281d78-d368-467e-868b-cb166c276b4f" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_012e27f6-c685-4952-b7ac-926b7601af65" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/RelatedPartyTransactionsNarrativeDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#RelatedPartyTransactionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/RelatedPartyTransactionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_59f6ce0d-ff5f-4b13-aaff-275d770fba26" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c8bfdc04-e4a3-41b7-a0b1-c1f49362c064" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_59f6ce0d-ff5f-4b13-aaff-275d770fba26" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c8bfdc04-e4a3-41b7-a0b1-c1f49362c064" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_5d395b74-6a72-4ba8-aaea-f78b504476fe" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c8bfdc04-e4a3-41b7-a0b1-c1f49362c064" xlink:to="loc_srt_OwnershipAxis_5d395b74-6a72-4ba8-aaea-f78b504476fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_5d395b74-6a72-4ba8-aaea-f78b504476fe_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_5d395b74-6a72-4ba8-aaea-f78b504476fe" xlink:to="loc_srt_OwnershipDomain_5d395b74-6a72-4ba8-aaea-f78b504476fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_e71ce5dd-2d61-4328-96be-caf438b5163d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_5d395b74-6a72-4ba8-aaea-f78b504476fe" xlink:to="loc_srt_OwnershipDomain_e71ce5dd-2d61-4328-96be-caf438b5163d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsGPHoldingsLPMember_41a08695-a166-460f-9d06-4c72bc978972" xlink:href="pagp-20231231.xsd#pagp_PlainsGPHoldingsLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_e71ce5dd-2d61-4328-96be-caf438b5163d" xlink:to="loc_pagp_PlainsGPHoldingsLPMember_41a08695-a166-460f-9d06-4c72bc978972" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAAPLPMember_eb91f5f6-7a04-4d7e-90a7-4090bb2fff5d" xlink:href="pagp-20231231.xsd#pagp_PlainsAAPLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_e71ce5dd-2d61-4328-96be-caf438b5163d" xlink:to="loc_pagp_PlainsAAPLPMember_eb91f5f6-7a04-4d7e-90a7-4090bb2fff5d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_8ce388a3-dbfa-4872-9049-cd2cb3a0720a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountByClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c8bfdc04-e4a3-41b7-a0b1-c1f49362c064" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_8ce388a3-dbfa-4872-9049-cd2cb3a0720a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_8ce388a3-dbfa-4872-9049-cd2cb3a0720a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_8ce388a3-dbfa-4872-9049-cd2cb3a0720a" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_8ce388a3-dbfa-4872-9049-cd2cb3a0720a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_f0589b6d-7d98-4bcd-bb7c-20b13f423943" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedPartnersCapitalAccountClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountByClassAxis_8ce388a3-dbfa-4872-9049-cd2cb3a0720a" xlink:to="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_f0589b6d-7d98-4bcd-bb7c-20b13f423943" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SharesClassCMember_c9cbd245-3eed-4b92-b196-7637a4c19150" xlink:href="pagp-20231231.xsd#pagp_SharesClassCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LimitedPartnersCapitalAccountClassDomain_f0589b6d-7d98-4bcd-bb7c-20b13f423943" xlink:to="loc_pagp_SharesClassCMember_c9cbd245-3eed-4b92-b196-7637a4c19150" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_a8050b07-364a-40c1-8eb8-0e3fe791ad50" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c8bfdc04-e4a3-41b7-a0b1-c1f49362c064" xlink:to="loc_dei_LegalEntityAxis_a8050b07-364a-40c1-8eb8-0e3fe791ad50" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_a8050b07-364a-40c1-8eb8-0e3fe791ad50_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_a8050b07-364a-40c1-8eb8-0e3fe791ad50" xlink:to="loc_dei_EntityDomain_a8050b07-364a-40c1-8eb8-0e3fe791ad50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_ee7b8959-d6f4-4579-bb7a-a967d540d7a0" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_a8050b07-364a-40c1-8eb8-0e3fe791ad50" xlink:to="loc_dei_EntityDomain_ee7b8959-d6f4-4579-bb7a-a967d540d7a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_a97a5a3b-e778-46ef-bd67-a0f2ebe7fc77" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_ee7b8959-d6f4-4579-bb7a-a967d540d7a0" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_a97a5a3b-e778-46ef-bd67-a0f2ebe7fc77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_bc6d4c87-89ec-4d8a-a38b-e990ce0fb22e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c8bfdc04-e4a3-41b7-a0b1-c1f49362c064" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_bc6d4c87-89ec-4d8a-a38b-e990ce0fb22e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_bc6d4c87-89ec-4d8a-a38b-e990ce0fb22e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_bc6d4c87-89ec-4d8a-a38b-e990ce0fb22e" xlink:to="loc_us-gaap_RelatedPartyDomain_bc6d4c87-89ec-4d8a-a38b-e990ce0fb22e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_24198ba5-1c06-4339-9a72-1abf3c0dcf28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_bc6d4c87-89ec-4d8a-a38b-e990ce0fb22e" xlink:to="loc_us-gaap_RelatedPartyDomain_24198ba5-1c06-4339-9a72-1abf3c0dcf28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrincipalOwnerMember_91b8febd-9fa6-4047-ba5b-ba5761b1d4a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrincipalOwnerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_24198ba5-1c06-4339-9a72-1abf3c0dcf28" xlink:to="loc_us-gaap_PrincipalOwnerMember_91b8febd-9fa6-4047-ba5b-ba5761b1d4a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_7ea894a9-4687-47a2-88b5-7c6dc95a6b8f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c8bfdc04-e4a3-41b7-a0b1-c1f49362c064" xlink:to="loc_srt_RangeAxis_7ea894a9-4687-47a2-88b5-7c6dc95a6b8f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7ea894a9-4687-47a2-88b5-7c6dc95a6b8f_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7ea894a9-4687-47a2-88b5-7c6dc95a6b8f" xlink:to="loc_srt_RangeMember_7ea894a9-4687-47a2-88b5-7c6dc95a6b8f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_44154dc9-14aa-4bf6-8864-72b64f91475e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7ea894a9-4687-47a2-88b5-7c6dc95a6b8f" xlink:to="loc_srt_RangeMember_44154dc9-14aa-4bf6-8864-72b64f91475e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_efcb702c-560a-473f-bd8d-4427e2c02207" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_44154dc9-14aa-4bf6-8864-72b64f91475e" xlink:to="loc_srt_MinimumMember_efcb702c-560a-473f-bd8d-4427e2c02207" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LimitedLiabilityCompanyLLCorLimitedPartnershipLPMembersorLimitedPartnersOwnershipInterestUnits_02e7c4b5-0d58-4348-a808-3305c63b07ea" xlink:href="pagp-20231231.xsd#pagp_LimitedLiabilityCompanyLLCorLimitedPartnershipLPMembersorLimitedPartnersOwnershipInterestUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_59f6ce0d-ff5f-4b13-aaff-275d770fba26" xlink:to="loc_pagp_LimitedLiabilityCompanyLLCorLimitedPartnershipLPMembersorLimitedPartnersOwnershipInterestUnits_02e7c4b5-0d58-4348-a808-3305c63b07ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest_85e10276-caba-40f6-b224-c22d1752c75c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_59f6ce0d-ff5f-4b13-aaff-275d770fba26" xlink:to="loc_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest_85e10276-caba-40f6-b224-c22d1752c75c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/RelatedPartyTransactionsTransactionswithOtherRelatedPartiesDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#RelatedPartyTransactionsTransactionswithOtherRelatedPartiesDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/RelatedPartyTransactionsTransactionswithOtherRelatedPartiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_505a7fd7-dab9-4dbe-8950-00bcd1e091d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_a45f75ff-12e9-40e0-9108-87d9b2f546b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_505a7fd7-dab9-4dbe-8950-00bcd1e091d7" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_a45f75ff-12e9-40e0-9108-87d9b2f546b9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6898927f-de86-43f8-bb51-836ccb1c5d88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_a45f75ff-12e9-40e0-9108-87d9b2f546b9" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6898927f-de86-43f8-bb51-836ccb1c5d88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_6898927f-de86-43f8-bb51-836ccb1c5d88_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6898927f-de86-43f8-bb51-836ccb1c5d88" xlink:to="loc_us-gaap_RelatedPartyDomain_6898927f-de86-43f8-bb51-836ccb1c5d88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_beafaa06-1d20-4fec-978c-eda2bb49d474" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6898927f-de86-43f8-bb51-836ccb1c5d88" xlink:to="loc_us-gaap_RelatedPartyDomain_beafaa06-1d20-4fec-978c-eda2bb49d474" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_d0280fdb-d8b3-436d-9cb4-a37b59deaa32" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_beafaa06-1d20-4fec-978c-eda2bb49d474" xlink:to="loc_srt_AffiliatedEntityMember_d0280fdb-d8b3-436d-9cb4-a37b59deaa32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_ab201cf4-ab76-4926-b15b-b6629a0ca1da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_505a7fd7-dab9-4dbe-8950-00bcd1e091d7" xlink:to="loc_us-gaap_Revenues_ab201cf4-ab76-4926-b15b-b6629a0ca1da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty_379fade0-f1bb-49ac-8f63-a059fceff551" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_505a7fd7-dab9-4dbe-8950-00bcd1e091d7" xlink:to="loc_us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty_379fade0-f1bb-49ac-8f63-a059fceff551" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesNetCurrent_652b93cb-ee4d-421f-a42d-48840069f1e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivablesNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_505a7fd7-dab9-4dbe-8950-00bcd1e091d7" xlink:to="loc_us-gaap_ReceivablesNetCurrent_652b93cb-ee4d-421f-a42d-48840069f1e6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableTradeCurrent_7c08d05b-ab23-40ce-a328-8979a472fc02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableTradeCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_505a7fd7-dab9-4dbe-8950-00bcd1e091d7" xlink:to="loc_us-gaap_AccountsPayableTradeCurrent_7c08d05b-ab23-40ce-a328-8979a472fc02" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/EquityIndexedCompensationPlansDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#EquityIndexedCompensationPlansDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/EquityIndexedCompensationPlansDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b0a607d4-dbc2-4f49-b9cb-297ac09dafdd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a85be9ac-1078-4b86-92c8-421354e95a99" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b0a607d4-dbc2-4f49-b9cb-297ac09dafdd" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a85be9ac-1078-4b86-92c8-421354e95a99" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_c3ade761-4af9-44f9-933e-f7fca264beec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a85be9ac-1078-4b86-92c8-421354e95a99" xlink:to="loc_us-gaap_PlanNameAxis_c3ade761-4af9-44f9-933e-f7fca264beec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_c3ade761-4af9-44f9-933e-f7fca264beec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_c3ade761-4af9-44f9-933e-f7fca264beec" xlink:to="loc_us-gaap_PlanNameDomain_c3ade761-4af9-44f9-933e-f7fca264beec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_e01103b2-0fd5-4bc4-a1a8-3f52e59f0d0f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_c3ade761-4af9-44f9-933e-f7fca264beec" xlink:to="loc_us-gaap_PlanNameDomain_e01103b2-0fd5-4bc4-a1a8-3f52e59f0d0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsGPHoldingsLongTermIncentivePlansMember_72b7f02f-6047-4daa-8d42-dbcbc125c87c" xlink:href="pagp-20231231.xsd#pagp_PlainsGPHoldingsLongTermIncentivePlansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_e01103b2-0fd5-4bc4-a1a8-3f52e59f0d0f" xlink:to="loc_pagp_PlainsGPHoldingsLongTermIncentivePlansMember_72b7f02f-6047-4daa-8d42-dbcbc125c87c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmerican2021LongTermIncentivePlanMember_498adf0d-5414-427b-833f-93e538fc92fc" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmerican2021LongTermIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_e01103b2-0fd5-4bc4-a1a8-3f52e59f0d0f" xlink:to="loc_pagp_PlainsAllAmerican2021LongTermIncentivePlanMember_498adf0d-5414-427b-833f-93e538fc92fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPNGSuccessorLongTermIncentivePlanMember_fdf981b4-ac85-4829-81bc-906f35c0b0dd" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPNGSuccessorLongTermIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_e01103b2-0fd5-4bc4-a1a8-3f52e59f0d0f" xlink:to="loc_pagp_PlainsAllAmericanPNGSuccessorLongTermIncentivePlanMember_fdf981b4-ac85-4829-81bc-906f35c0b0dd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanGPLLCLongTermIncentiveTrackingUnitPlanMember_4061a7b7-a510-4b24-a4a1-aeeb75e09251" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanGPLLCLongTermIncentiveTrackingUnitPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_e01103b2-0fd5-4bc4-a1a8-3f52e59f0d0f" xlink:to="loc_pagp_PlainsAllAmericanGPLLCLongTermIncentiveTrackingUnitPlanMember_4061a7b7-a510-4b24-a4a1-aeeb75e09251" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanLongTermIncentivePlansMember_a4887138-59df-4ce0-b19c-749a3d365855" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanLongTermIncentivePlansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_e01103b2-0fd5-4bc4-a1a8-3f52e59f0d0f" xlink:to="loc_pagp_PlainsAllAmericanLongTermIncentivePlansMember_a4887138-59df-4ce0-b19c-749a3d365855" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_16ebf767-b583-4197-bb96-75c1f06ea991" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a85be9ac-1078-4b86-92c8-421354e95a99" xlink:to="loc_dei_LegalEntityAxis_16ebf767-b583-4197-bb96-75c1f06ea991" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_16ebf767-b583-4197-bb96-75c1f06ea991_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_16ebf767-b583-4197-bb96-75c1f06ea991" xlink:to="loc_dei_EntityDomain_16ebf767-b583-4197-bb96-75c1f06ea991_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_5369147e-9471-48e5-9407-6939a6557faa" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_16ebf767-b583-4197-bb96-75c1f06ea991" xlink:to="loc_dei_EntityDomain_5369147e-9471-48e5-9407-6939a6557faa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_PlainsAllAmericanPipelineLPMember_7e3f9108-daf1-4d1e-840b-d5d09325999f" xlink:href="pagp-20231231.xsd#pagp_PlainsAllAmericanPipelineLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_5369147e-9471-48e5-9407-6939a6557faa" xlink:to="loc_pagp_PlainsAllAmericanPipelineLPMember_7e3f9108-daf1-4d1e-840b-d5d09325999f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_497bca71-3d77-4321-95a4-28118060b424" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b0a607d4-dbc2-4f49-b9cb-297ac09dafdd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_497bca71-3d77-4321-95a4-28118060b424" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_bcb3a611-b9b6-4d2e-85b4-57ed4a2efe90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b0a607d4-dbc2-4f49-b9cb-297ac09dafdd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_bcb3a611-b9b6-4d2e-85b4-57ed4a2efe90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_88363d1f-433a-4153-b211-539a3ada2236" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b0a607d4-dbc2-4f49-b9cb-297ac09dafdd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_88363d1f-433a-4153-b211-539a3ada2236" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsIncludingDistributionEquivalentRightsOutstanding_d04b2ea1-10f0-4379-8d94-faf93906152f" xlink:href="pagp-20231231.xsd#pagp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsIncludingDistributionEquivalentRightsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b0a607d4-dbc2-4f49-b9cb-297ac09dafdd" xlink:to="loc_pagp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsIncludingDistributionEquivalentRightsOutstanding_d04b2ea1-10f0-4379-8d94-faf93906152f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsProbableVestingUnrecognizedFairValue_50c03647-c35d-4eea-8b65-a776764aba9b" xlink:href="pagp-20231231.xsd#pagp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsProbableVestingUnrecognizedFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b0a607d4-dbc2-4f49-b9cb-297ac09dafdd" xlink:to="loc_pagp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsProbableVestingUnrecognizedFairValue_50c03647-c35d-4eea-8b65-a776764aba9b" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/CommitmentsandContingenciesLegalEnvironmentalorRegulatoryDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#CommitmentsandContingenciesLegalEnvironmentalorRegulatoryDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/CommitmentsandContingenciesLegalEnvironmentalorRegulatoryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_dc4ee615-33fc-45e5-8316-fc943b28b3f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_LossContingenciesTable_dc4ee615-33fc-45e5-8316-fc943b28b3f2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalRemediationContingencyAxis_e019fbc9-d225-4b99-a79b-39cad00f73ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EnvironmentalRemediationContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dc4ee615-33fc-45e5-8316-fc943b28b3f2" xlink:to="loc_us-gaap_EnvironmentalRemediationContingencyAxis_e019fbc9-d225-4b99-a79b-39cad00f73ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalRemediationContingencyDomain_e019fbc9-d225-4b99-a79b-39cad00f73ee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EnvironmentalRemediationContingencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EnvironmentalRemediationContingencyAxis_e019fbc9-d225-4b99-a79b-39cad00f73ee" xlink:to="loc_us-gaap_EnvironmentalRemediationContingencyDomain_e019fbc9-d225-4b99-a79b-39cad00f73ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalRemediationContingencyDomain_906df649-cbb0-49fe-888c-5348ca166b32" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EnvironmentalRemediationContingencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EnvironmentalRemediationContingencyAxis_e019fbc9-d225-4b99-a79b-39cad00f73ee" xlink:to="loc_us-gaap_EnvironmentalRemediationContingencyDomain_906df649-cbb0-49fe-888c-5348ca166b32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ExcludingLine901IncidentMember_5a6aeb4f-d9b7-4688-a929-f94fff31025e" xlink:href="pagp-20231231.xsd#pagp_ExcludingLine901IncidentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalRemediationContingencyDomain_906df649-cbb0-49fe-888c-5348ca166b32" xlink:to="loc_pagp_ExcludingLine901IncidentMember_5a6aeb4f-d9b7-4688-a929-f94fff31025e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_60c7cb34-ccdf-4390-8d30-450ba8240952" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dc4ee615-33fc-45e5-8316-fc943b28b3f2" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_60c7cb34-ccdf-4390-8d30-450ba8240952" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_60c7cb34-ccdf-4390-8d30-450ba8240952_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_60c7cb34-ccdf-4390-8d30-450ba8240952" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_60c7cb34-ccdf-4390-8d30-450ba8240952_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_1c105489-ae2f-40c3-a43a-dcb3b4fb99ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_60c7cb34-ccdf-4390-8d30-450ba8240952" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_1c105489-ae2f-40c3-a43a-dcb3b4fb99ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CurrentLiabilitiesMember_52cdcda9-500b-42d4-9406-97455c861b85" xlink:href="pagp-20231231.xsd#pagp_CurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_1c105489-ae2f-40c3-a43a-dcb3b4fb99ea" xlink:to="loc_pagp_CurrentLiabilitiesMember_52cdcda9-500b-42d4-9406-97455c861b85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_913cd6e0-169b-4a48-9060-38f134709406" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoncurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_1c105489-ae2f-40c3-a43a-dcb3b4fb99ea" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_913cd6e0-169b-4a48-9060-38f134709406" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_203452f4-3a58-4655-a01a-95ae1d658921" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dc4ee615-33fc-45e5-8316-fc943b28b3f2" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_203452f4-3a58-4655-a01a-95ae1d658921" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_203452f4-3a58-4655-a01a-95ae1d658921_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_203452f4-3a58-4655-a01a-95ae1d658921" xlink:to="loc_us-gaap_LossContingencyNatureDomain_203452f4-3a58-4655-a01a-95ae1d658921_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_7a681459-e66d-470f-9c8f-c7ab16f9e1b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_203452f4-3a58-4655-a01a-95ae1d658921" xlink:to="loc_us-gaap_LossContingencyNatureDomain_7a681459-e66d-470f-9c8f-c7ab16f9e1b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_Line901IncidentMember_068a2c27-cba6-4782-853c-103623405871" xlink:href="pagp-20231231.xsd#pagp_Line901IncidentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_7a681459-e66d-470f-9c8f-c7ab16f9e1b8" xlink:to="loc_pagp_Line901IncidentMember_068a2c27-cba6-4782-853c-103623405871" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_Line9012015InsuranceProgramMember_e69ea02e-f3c0-48f4-a697-ab63c885a2c7" xlink:href="pagp-20231231.xsd#pagp_Line9012015InsuranceProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_Line901IncidentMember_068a2c27-cba6-4782-853c-103623405871" xlink:to="loc_pagp_Line9012015InsuranceProgramMember_e69ea02e-f3c0-48f4-a697-ab63c885a2c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ClaimForReimbursementFromInsuranceMember_d25cb9b7-4fc2-477a-a53e-4ba9226a5161" xlink:href="pagp-20231231.xsd#pagp_ClaimForReimbursementFromInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_Line9012015InsuranceProgramMember_e69ea02e-f3c0-48f4-a697-ab63c885a2c7" xlink:to="loc_pagp_ClaimForReimbursementFromInsuranceMember_d25cb9b7-4fc2-477a-a53e-4ba9226a5161" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DenialOfInsuranceCoverageMember_91535e66-3577-49ca-9d4e-c56e7588e710" xlink:href="pagp-20231231.xsd#pagp_DenialOfInsuranceCoverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ClaimForReimbursementFromInsuranceMember_d25cb9b7-4fc2-477a-a53e-4ba9226a5161" xlink:to="loc_pagp_DenialOfInsuranceCoverageMember_91535e66-3577-49ca-9d4e-c56e7588e710" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ResponseToRequestForReimbursementNotReceivedMember_6a7ec278-179a-4438-90d1-c4c4f5099eae" xlink:href="pagp-20231231.xsd#pagp_ResponseToRequestForReimbursementNotReceivedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ClaimForReimbursementFromInsuranceMember_d25cb9b7-4fc2-477a-a53e-4ba9226a5161" xlink:to="loc_pagp_ResponseToRequestForReimbursementNotReceivedMember_6a7ec278-179a-4438-90d1-c4c4f5099eae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ArbitrationProceedingsAgainstInsurersMember_203bd0a1-94d9-4293-88c6-b17a1cadf0d0" xlink:href="pagp-20231231.xsd#pagp_ArbitrationProceedingsAgainstInsurersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pagp_ClaimForReimbursementFromInsuranceMember_d25cb9b7-4fc2-477a-a53e-4ba9226a5161" xlink:to="loc_pagp_ArbitrationProceedingsAgainstInsurersMember_203bd0a1-94d9-4293-88c6-b17a1cadf0d0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_5e5234fe-9b13-4815-81cd-d6b2bb1c2d1e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dc4ee615-33fc-45e5-8316-fc943b28b3f2" xlink:to="loc_srt_LitigationCaseAxis_5e5234fe-9b13-4815-81cd-d6b2bb1c2d1e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_5e5234fe-9b13-4815-81cd-d6b2bb1c2d1e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_5e5234fe-9b13-4815-81cd-d6b2bb1c2d1e" xlink:to="loc_srt_LitigationCaseTypeDomain_5e5234fe-9b13-4815-81cd-d6b2bb1c2d1e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_36bae6d0-38df-494f-aee1-8398692b4af9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_5e5234fe-9b13-4815-81cd-d6b2bb1c2d1e" xlink:to="loc_srt_LitigationCaseTypeDomain_36bae6d0-38df-494f-aee1-8398692b4af9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ConsentDecreeCivilPenaltiesMember_c357d66d-a456-45f5-b7bf-918f8e7057d1" xlink:href="pagp-20231231.xsd#pagp_ConsentDecreeCivilPenaltiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_36bae6d0-38df-494f-aee1-8398692b4af9" xlink:to="loc_pagp_ConsentDecreeCivilPenaltiesMember_c357d66d-a456-45f5-b7bf-918f8e7057d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ConsentDecreeCompensationForInjuriesToDestructionOfLossOfUseOfNaturalResourcesMember_0ca47eda-4d48-4ee7-8266-f37ee612a65d" xlink:href="pagp-20231231.xsd#pagp_ConsentDecreeCompensationForInjuriesToDestructionOfLossOfUseOfNaturalResourcesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_36bae6d0-38df-494f-aee1-8398692b4af9" xlink:to="loc_pagp_ConsentDecreeCompensationForInjuriesToDestructionOfLossOfUseOfNaturalResourcesMember_0ca47eda-4d48-4ee7-8266-f37ee612a65d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IndictmentInCaliforniaSuperiorCourtSantaBarbaraCountyMember_c017c7e3-9af5-483b-82c0-2ce5f7813737" xlink:href="pagp-20231231.xsd#pagp_IndictmentInCaliforniaSuperiorCourtSantaBarbaraCountyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_36bae6d0-38df-494f-aee1-8398692b4af9" xlink:to="loc_pagp_IndictmentInCaliforniaSuperiorCourtSantaBarbaraCountyMember_c017c7e3-9af5-483b-82c0-2ce5f7813737" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_ClassActionLawsuitClaimOfDamagesMember_200a4228-0937-4bf1-ac87-49a49c979a34" xlink:href="pagp-20231231.xsd#pagp_ClassActionLawsuitClaimOfDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_36bae6d0-38df-494f-aee1-8398692b4af9" xlink:to="loc_pagp_ClassActionLawsuitClaimOfDamagesMember_200a4228-0937-4bf1-ac87-49a49c979a34" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_460b81f7-3ac6-41f3-849c-e1e490db3e24" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dc4ee615-33fc-45e5-8316-fc943b28b3f2" xlink:to="loc_us-gaap_LitigationStatusAxis_460b81f7-3ac6-41f3-849c-e1e490db3e24" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_460b81f7-3ac6-41f3-849c-e1e490db3e24_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_460b81f7-3ac6-41f3-849c-e1e490db3e24" xlink:to="loc_us-gaap_LitigationStatusDomain_460b81f7-3ac6-41f3-849c-e1e490db3e24_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_2648e7a7-d800-493d-a43e-8920235cef41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_460b81f7-3ac6-41f3-849c-e1e490db3e24" xlink:to="loc_us-gaap_LitigationStatusDomain_2648e7a7-d800-493d-a43e-8920235cef41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JudicialRulingMember_6a420e75-9466-411a-a358-32e9fa555ef9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JudicialRulingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_2648e7a7-d800-493d-a43e-8920235cef41" xlink:to="loc_us-gaap_JudicialRulingMember_6a420e75-9466-411a-a358-32e9fa555ef9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SettledLitigationMember_3e83da0a-33b7-4850-b75b-2e6076512a48" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SettledLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_2648e7a7-d800-493d-a43e-8920235cef41" xlink:to="loc_us-gaap_SettledLitigationMember_3e83da0a-33b7-4850-b75b-2e6076512a48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_8eb12001-5a0f-400b-a67d-bf8bc1e27e2a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_2648e7a7-d800-493d-a43e-8920235cef41" xlink:to="loc_us-gaap_PendingLitigationMember_8eb12001-5a0f-400b-a67d-bf8bc1e27e2a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_7375c202-829d-4d27-a0c9-eaea2fddfb3d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_dc4ee615-33fc-45e5-8316-fc943b28b3f2" xlink:to="loc_srt_RangeAxis_7375c202-829d-4d27-a0c9-eaea2fddfb3d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7375c202-829d-4d27-a0c9-eaea2fddfb3d_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7375c202-829d-4d27-a0c9-eaea2fddfb3d" xlink:to="loc_srt_RangeMember_7375c202-829d-4d27-a0c9-eaea2fddfb3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3d79e516-0c7c-4756-9ead-01e0ec42b8f4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7375c202-829d-4d27-a0c9-eaea2fddfb3d" xlink:to="loc_srt_RangeMember_3d79e516-0c7c-4756-9ead-01e0ec42b8f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_30d4b957-100f-455e-a5f3-8813d722bd05" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3d79e516-0c7c-4756-9ead-01e0ec42b8f4" xlink:to="loc_srt_MaximumMember_30d4b957-100f-455e-a5f3-8813d722bd05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccrualForEnvironmentalLossContingenciesGross_96e05ca3-ace1-4d44-993e-6d0c11954844" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccrualForEnvironmentalLossContingenciesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_AccrualForEnvironmentalLossContingenciesGross_96e05ca3-ace1-4d44-993e-6d0c11954844" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEnvironmentalLossContingenciesCurrent_249135c7-ee83-4983-99fe-9374ebc1c0b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedEnvironmentalLossContingenciesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_AccruedEnvironmentalLossContingenciesCurrent_249135c7-ee83-4983-99fe-9374ebc1c0b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalLossContingencyCurrentStatementOfFinancialPositionExtensibleEnumeration_f1b5f5a1-8f48-4c14-b925-7b6b0bd2bf89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EnvironmentalLossContingencyCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccruedEnvironmentalLossContingenciesCurrent_249135c7-ee83-4983-99fe-9374ebc1c0b1" xlink:to="loc_us-gaap_EnvironmentalLossContingencyCurrentStatementOfFinancialPositionExtensibleEnumeration_f1b5f5a1-8f48-4c14-b925-7b6b0bd2bf89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_e3b5a73d-26f4-4717-848f-bfdf48da3cf4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_e3b5a73d-26f4-4717-848f-bfdf48da3cf4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalLossContingencyNoncurrentStatementOfFinancialPositionExtensibleEnumeration_21bbe1ef-a5b7-48fb-aa7c-0c163e36ab0c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EnvironmentalLossContingencyNoncurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_e3b5a73d-26f4-4717-848f-bfdf48da3cf4" xlink:to="loc_us-gaap_EnvironmentalLossContingencyNoncurrentStatementOfFinancialPositionExtensibleEnumeration_21bbe1ef-a5b7-48fb-aa7c-0c163e36ab0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RecordedThirdPartyEnvironmentalRecoveriesReceivable_7e0cc48d-8b69-429c-8eb7-8d009a242273" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RecordedThirdPartyEnvironmentalRecoveriesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_RecordedThirdPartyEnvironmentalRecoveriesReceivable_7e0cc48d-8b69-429c-8eb7-8d009a242273" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EstimatedSizeOfRelease_8c8c950f-7ca0-446c-a79d-2057ac1f32b8" xlink:href="pagp-20231231.xsd#pagp_EstimatedSizeOfRelease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_EstimatedSizeOfRelease_8c8c950f-7ca0-446c-a79d-2057ac1f32b8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EstimatedSizeOfReleaseToReachBodyOfWater_6180e836-11f9-4ad5-8ba2-848ccf1a5258" xlink:href="pagp-20231231.xsd#pagp_EstimatedSizeOfReleaseToReachBodyOfWater"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_EstimatedSizeOfReleaseToReachBodyOfWater_6180e836-11f9-4ad5-8ba2-848ccf1a5258" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesPaidValue_2a3acbc7-92c8-4167-90f6-f254a0c1b630" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyDamagesPaidValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_LossContingencyDamagesPaidValue_2a3acbc7-92c8-4167-90f6-f254a0c1b630" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IndictmentNumberofFelonyChargesGuiltyVerdict_3b84bc00-9937-425a-b329-2c6b64a38fbe" xlink:href="pagp-20231231.xsd#pagp_IndictmentNumberofFelonyChargesGuiltyVerdict"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_IndictmentNumberofFelonyChargesGuiltyVerdict_3b84bc00-9937-425a-b329-2c6b64a38fbe" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdict_521a12a5-43c0-4bb5-94a8-392516696af4" xlink:href="pagp-20231231.xsd#pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdict"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdict_521a12a5-43c0-4bb5-94a8-392516696af4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictReportingCount_9c889317-db92-4dd6-9fdc-f6a8bd5da475" xlink:href="pagp-20231231.xsd#pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictReportingCount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictReportingCount_9c889317-db92-4dd6-9fdc-f6a8bd5da475" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictStrictLiabilityDischargeCount_7d57c400-fcf5-4d35-a411-338e7c2809bd" xlink:href="pagp-20231231.xsd#pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictStrictLiabilityDischargeCount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictStrictLiabilityDischargeCount_7d57c400-fcf5-4d35-a411-338e7c2809bd" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictStrictLiabilityAnimalTakingsCount_0a4e7916-84d7-4aed-b391-0cbebc9b5999" xlink:href="pagp-20231231.xsd#pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictStrictLiabilityAnimalTakingsCount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_IndictmentNumberofMisdemeanorChargesGuiltyVerdictStrictLiabilityAnimalTakingsCount_0a4e7916-84d7-4aed-b391-0cbebc9b5999" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_IndictmentNumberofMisdemeanorChargesNotGuiltyVerdictStrictLiabilityAnimalTakingsCount_a25407a0-18c3-40e7-891d-78dd6b6f6a25" xlink:href="pagp-20231231.xsd#pagp_IndictmentNumberofMisdemeanorChargesNotGuiltyVerdictStrictLiabilityAnimalTakingsCount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_IndictmentNumberofMisdemeanorChargesNotGuiltyVerdictStrictLiabilityAnimalTakingsCount_a25407a0-18c3-40e7-891d-78dd6b6f6a25" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LossContingencyPenaltyOrFineAssessed_d2056be0-82a1-4885-b5fc-8f1a5bb13c3c" xlink:href="pagp-20231231.xsd#pagp_LossContingencyPenaltyOrFineAssessed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_LossContingencyPenaltyOrFineAssessed_d2056be0-82a1-4885-b5fc-8f1a5bb13c3c" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesAwardedValue_7b22e293-b3b5-40ce-bf56-22cd395f2ed1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyDamagesAwardedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_LossContingencyDamagesAwardedValue_7b22e293-b3b5-40ce-bf56-22cd395f2ed1" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LitigationSettlementAmountAgreedUponSubjectToApproval_1e3b9017-02aa-4371-a2fa-fd442ce6954e" xlink:href="pagp-20231231.xsd#pagp_LitigationSettlementAmountAgreedUponSubjectToApproval"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_LitigationSettlementAmountAgreedUponSubjectToApproval_1e3b9017-02aa-4371-a2fa-fd442ce6954e" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_0e664494-7b27-4a29-947d-324846819074" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_0e664494-7b27-4a29-947d-324846819074" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivableProceeds_f313619c-a7c0-48c6-a63b-9fee0110a8a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyReceivableProceeds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_LossContingencyReceivableProceeds_f313619c-a7c0-48c6-a63b-9fee0110a8a0" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InsuranceCoverageLimit_a0be4b5f-c97f-4cd9-9c0f-6e5696217c90" xlink:href="pagp-20231231.xsd#pagp_InsuranceCoverageLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_InsuranceCoverageLimit_a0be4b5f-c97f-4cd9-9c0f-6e5696217c90" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivable_93bb7a02-66ca-4b30-ad74-db7b3331b173" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_LossContingencyReceivable_93bb7a02-66ca-4b30-ad74-db7b3331b173" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_b89aa310-807b-4593-b09d-aabaf3bd4f6b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_b89aa310-807b-4593-b09d-aabaf3bd4f6b" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SignificantCostsRelatedToLegalAndEnvironmentalRemediationMatters_635d458d-31c4-4393-a9b8-d2998989c61c" xlink:href="pagp-20231231.xsd#pagp_SignificantCostsRelatedToLegalAndEnvironmentalRemediationMatters"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_SignificantCostsRelatedToLegalAndEnvironmentalRemediationMatters_635d458d-31c4-4393-a9b8-d2998989c61c" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_9b35a385-811f-4b5d-8522-609c5e996e2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_9b35a385-811f-4b5d-8522-609c5e996e2f" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LossContingencyExceededInsuranceCoverageLimit_3018bf62-2b49-4d3e-a4ff-f793291a7440" xlink:href="pagp-20231231.xsd#pagp_LossContingencyExceededInsuranceCoverageLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_LossContingencyExceededInsuranceCoverageLimit_3018bf62-2b49-4d3e-a4ff-f793291a7440" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LossContingencyReceivedAndReceivable_6781e9f7-e6fd-4c12-8117-88c9524b6671" xlink:href="pagp-20231231.xsd#pagp_LossContingencyReceivedAndReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_f7971b08-a355-4685-9f07-54d6045c88e4" xlink:to="loc_pagp_LossContingencyReceivedAndReceivable_6781e9f7-e6fd-4c12-8117-88c9524b6671" xlink:type="arc" order="24"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/SegmentInformationSegmentFinancialDataDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#SegmentInformationSegmentFinancialDataDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/SegmentInformationSegmentFinancialDataDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_754abf58-52c0-4496-ba31-a1be5cf8a19a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_395813b3-b74a-4524-a766-a6f159794e89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_754abf58-52c0-4496-ba31-a1be5cf8a19a" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_395813b3-b74a-4524-a766-a6f159794e89" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_81d6132c-0397-43e4-b8d5-fdb8fa783a25" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_395813b3-b74a-4524-a766-a6f159794e89" xlink:to="loc_srt_ConsolidationItemsAxis_81d6132c-0397-43e4-b8d5-fdb8fa783a25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_81d6132c-0397-43e4-b8d5-fdb8fa783a25_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_81d6132c-0397-43e4-b8d5-fdb8fa783a25" xlink:to="loc_srt_ConsolidationItemsDomain_81d6132c-0397-43e4-b8d5-fdb8fa783a25_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_611484a0-5a8a-4f82-92f8-20ac0d6303b8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_81d6132c-0397-43e4-b8d5-fdb8fa783a25" xlink:to="loc_srt_ConsolidationItemsDomain_611484a0-5a8a-4f82-92f8-20ac0d6303b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_faf0d537-8185-4c67-9078-ccad223796d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_611484a0-5a8a-4f82-92f8-20ac0d6303b8" xlink:to="loc_us-gaap_OperatingSegmentsMember_faf0d537-8185-4c67-9078-ccad223796d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_12dccd2e-8db8-45cd-95ce-847a14f28cc6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_611484a0-5a8a-4f82-92f8-20ac0d6303b8" xlink:to="loc_us-gaap_IntersegmentEliminationMember_12dccd2e-8db8-45cd-95ce-847a14f28cc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_c1e5e109-4298-4aa7-abbd-1e0a958e377d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_395813b3-b74a-4524-a766-a6f159794e89" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_c1e5e109-4298-4aa7-abbd-1e0a958e377d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_c1e5e109-4298-4aa7-abbd-1e0a958e377d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_c1e5e109-4298-4aa7-abbd-1e0a958e377d" xlink:to="loc_us-gaap_SegmentDomain_c1e5e109-4298-4aa7-abbd-1e0a958e377d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_96b4105c-ee4a-4a3f-8c5d-3fe2ba759b6f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_c1e5e109-4298-4aa7-abbd-1e0a958e377d" xlink:to="loc_us-gaap_SegmentDomain_96b4105c-ee4a-4a3f-8c5d-3fe2ba759b6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_CrudeOilSegmentMember_91d30c64-8597-41c9-8530-8ef25b114923" xlink:href="pagp-20231231.xsd#pagp_CrudeOilSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_96b4105c-ee4a-4a3f-8c5d-3fe2ba759b6f" xlink:to="loc_pagp_CrudeOilSegmentMember_91d30c64-8597-41c9-8530-8ef25b114923" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NaturalGasLiquidsSegmentMember_12bf1e6d-e658-41e2-ae83-2b7a0debfab4" xlink:href="pagp-20231231.xsd#pagp_NaturalGasLiquidsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_96b4105c-ee4a-4a3f-8c5d-3fe2ba759b6f" xlink:to="loc_pagp_NaturalGasLiquidsSegmentMember_12bf1e6d-e658-41e2-ae83-2b7a0debfab4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_3f95dda1-16b2-4e54-8a10-7b1bdecf9d48" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_395813b3-b74a-4524-a766-a6f159794e89" xlink:to="loc_srt_ProductOrServiceAxis_3f95dda1-16b2-4e54-8a10-7b1bdecf9d48" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_3f95dda1-16b2-4e54-8a10-7b1bdecf9d48_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_3f95dda1-16b2-4e54-8a10-7b1bdecf9d48" xlink:to="loc_srt_ProductsAndServicesDomain_3f95dda1-16b2-4e54-8a10-7b1bdecf9d48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_77b23fc0-8963-40d4-8085-a8ed7ccf8bf0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_3f95dda1-16b2-4e54-8a10-7b1bdecf9d48" xlink:to="loc_srt_ProductsAndServicesDomain_77b23fc0-8963-40d4-8085-a8ed7ccf8bf0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_7338bd83-084a-460a-9a16-08262efe5753" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_77b23fc0-8963-40d4-8085-a8ed7ccf8bf0" xlink:to="loc_us-gaap_ProductMember_7338bd83-084a-460a-9a16-08262efe5753" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_8bba2425-ee53-491f-969b-dbb85597b6e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_77b23fc0-8963-40d4-8085-a8ed7ccf8bf0" xlink:to="loc_us-gaap_ServiceMember_8bba2425-ee53-491f-969b-dbb85597b6e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationRevenueAbstract_c3528982-2a63-4bbf-896a-c4db7db2de62" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationRevenueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_754abf58-52c0-4496-ba31-a1be5cf8a19a" xlink:to="loc_us-gaap_SegmentReportingInformationRevenueAbstract_c3528982-2a63-4bbf-896a-c4db7db2de62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_a91d65de-b9f6-40a9-95a8-0f018781eba0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_c3528982-2a63-4bbf-896a-c4db7db2de62" xlink:to="loc_us-gaap_Revenues_a91d65de-b9f6-40a9-95a8-0f018781eba0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingDisclosureOfOtherInformationAboutEntitysReportableSegmentsAbstract_5811ab3c-0249-4ab5-aa7c-4328126d1a5e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingDisclosureOfOtherInformationAboutEntitysReportableSegmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_754abf58-52c0-4496-ba31-a1be5cf8a19a" xlink:to="loc_us-gaap_SegmentReportingDisclosureOfOtherInformationAboutEntitysReportableSegmentsAbstract_5811ab3c-0249-4ab5-aa7c-4328126d1a5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_f58a2580-5c52-4fea-9a2b-e6a3b720a2df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingDisclosureOfOtherInformationAboutEntitysReportableSegmentsAbstract_5811ab3c-0249-4ab5-aa7c-4328126d1a5e" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_f58a2580-5c52-4fea-9a2b-e6a3b720a2df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SegmentAdjustedEBITDA_ae7a44d2-b53a-415f-a92a-bb6b9a499a91" xlink:href="pagp-20231231.xsd#pagp_SegmentAdjustedEBITDA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingDisclosureOfOtherInformationAboutEntitysReportableSegmentsAbstract_5811ab3c-0249-4ab5-aa7c-4328126d1a5e" xlink:to="loc_pagp_SegmentAdjustedEBITDA_ae7a44d2-b53a-415f-a92a-bb6b9a499a91" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_InvestmentAndAcquisitionCapitalExpenditures_a145502c-a251-4e13-9b99-895491d7eb30" xlink:href="pagp-20231231.xsd#pagp_InvestmentAndAcquisitionCapitalExpenditures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingDisclosureOfOtherInformationAboutEntitysReportableSegmentsAbstract_5811ab3c-0249-4ab5-aa7c-4328126d1a5e" xlink:to="loc_pagp_InvestmentAndAcquisitionCapitalExpenditures_a145502c-a251-4e13-9b99-895491d7eb30" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_MaintenanceCapitalExpenditures_ed2fe982-51e9-42a3-9f69-b53085af57df" xlink:href="pagp-20231231.xsd#pagp_MaintenanceCapitalExpenditures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingDisclosureOfOtherInformationAboutEntitysReportableSegmentsAbstract_5811ab3c-0249-4ab5-aa7c-4328126d1a5e" xlink:to="loc_pagp_MaintenanceCapitalExpenditures_ed2fe982-51e9-42a3-9f69-b53085af57df" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_da7e5190-9b2f-4608-b22e-a1f1574371e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingDisclosureOfOtherInformationAboutEntitysReportableSegmentsAbstract_5811ab3c-0249-4ab5-aa7c-4328126d1a5e" xlink:to="loc_us-gaap_EquityMethodInvestments_da7e5190-9b2f-4608-b22e-a1f1574371e1" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/SegmentInformationReconciliationofSegmentAdjustedEBITDADetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#SegmentInformationReconciliationofSegmentAdjustedEBITDADetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/SegmentInformationReconciliationofSegmentAdjustedEBITDADetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_05e0c745-4861-452c-a6dd-67349fea2291" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_b124d6c8-63b8-42a8-be25-97457e0c067e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_05e0c745-4861-452c-a6dd-67349fea2291" xlink:to="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_b124d6c8-63b8-42a8-be25-97457e0c067e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_24630abb-787d-442c-9d14-0a26f4fda933" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_b124d6c8-63b8-42a8-be25-97457e0c067e" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_24630abb-787d-442c-9d14-0a26f4fda933" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_24630abb-787d-442c-9d14-0a26f4fda933_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_24630abb-787d-442c-9d14-0a26f4fda933" xlink:to="loc_us-gaap_LossContingencyNatureDomain_24630abb-787d-442c-9d14-0a26f4fda933_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_6cf10670-9def-4958-a4f0-9b9681865c94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_24630abb-787d-442c-9d14-0a26f4fda933" xlink:to="loc_us-gaap_LossContingencyNatureDomain_6cf10670-9def-4958-a4f0-9b9681865c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_Line901IncidentMember_9e03ee18-2d98-4224-92ca-c667303989b1" xlink:href="pagp-20231231.xsd#pagp_Line901IncidentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_6cf10670-9def-4958-a4f0-9b9681865c94" xlink:to="loc_pagp_Line901IncidentMember_9e03ee18-2d98-4224-92ca-c667303989b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_6d45d202-12cc-4c8d-a7d1-b56dc9b53c23" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_b124d6c8-63b8-42a8-be25-97457e0c067e" xlink:to="loc_srt_ConsolidationItemsAxis_6d45d202-12cc-4c8d-a7d1-b56dc9b53c23" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_6d45d202-12cc-4c8d-a7d1-b56dc9b53c23_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_6d45d202-12cc-4c8d-a7d1-b56dc9b53c23" xlink:to="loc_srt_ConsolidationItemsDomain_6d45d202-12cc-4c8d-a7d1-b56dc9b53c23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_3b19f135-89cc-40b0-9bfa-39e3136dc5ec" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_6d45d202-12cc-4c8d-a7d1-b56dc9b53c23" xlink:to="loc_srt_ConsolidationItemsDomain_3b19f135-89cc-40b0-9bfa-39e3136dc5ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_e68b2378-bde2-4f70-8dbf-51783f2f1180" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_3b19f135-89cc-40b0-9bfa-39e3136dc5ec" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_e68b2378-bde2-4f70-8dbf-51783f2f1180" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SegmentAdjustedEBITDA_3bda505c-c00d-4788-9fc7-8e2e41aedf44" xlink:href="pagp-20231231.xsd#pagp_SegmentAdjustedEBITDA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_05e0c745-4861-452c-a6dd-67349fea2291" xlink:to="loc_pagp_SegmentAdjustedEBITDA_3bda505c-c00d-4788-9fc7-8e2e41aedf44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_05e0c745-4861-452c-a6dd-67349fea2291" xlink:to="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DepreciationAndAmortizationOfUnconsolidatedEntities_9d3a9668-87e8-4ae7-8f4e-c51f067d5c6d" xlink:href="pagp-20231231.xsd#pagp_DepreciationAndAmortizationOfUnconsolidatedEntities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_DepreciationAndAmortizationOfUnconsolidatedEntities_9d3a9668-87e8-4ae7-8f4e-c51f067d5c6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainsLossesFromDerivativeActivitiesNetofInventoryValuationAdjustments_023b485e-97f7-4f21-b968-b6f995892fe3" xlink:href="pagp-20231231.xsd#pagp_GainsLossesFromDerivativeActivitiesNetofInventoryValuationAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_GainsLossesFromDerivativeActivitiesNetofInventoryValuationAdjustments_023b485e-97f7-4f21-b968-b6f995892fe3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_LongTermInventoryCostingAdjustments_7062d4fe-1d0c-4754-b428-d83d355cc333" xlink:href="pagp-20231231.xsd#pagp_LongTermInventoryCostingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_LongTermInventoryCostingAdjustments_7062d4fe-1d0c-4754-b428-d83d355cc333" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_DeficienciesUnderMinimumVolumeCommitmentsNet_f8beb64b-f7b2-4f64-8c19-5cb1488f80b9" xlink:href="pagp-20231231.xsd#pagp_DeficienciesUnderMinimumVolumeCommitmentsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_DeficienciesUnderMinimumVolumeCommitmentsNet_f8beb64b-f7b2-4f64-8c19-5cb1488f80b9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_EquityIndexedCompensationExpenseAwardsThatWillOrMayBeSettledInUnits_b8bc6437-700b-414a-866a-0348fe80a478" xlink:href="pagp-20231231.xsd#pagp_EquityIndexedCompensationExpenseAwardsThatWillOrMayBeSettledInUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_EquityIndexedCompensationExpenseAwardsThatWillOrMayBeSettledInUnits_b8bc6437-700b-414a-866a-0348fe80a478" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_NetGainLossOnForeignCurrencyRevaluation_e05bf4ba-d9c5-48c1-aa12-67c2d1205e6b" xlink:href="pagp-20231231.xsd#pagp_NetGainLossOnForeignCurrencyRevaluation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_NetGainLossOnForeignCurrencyRevaluation_e05bf4ba-d9c5-48c1-aa12-67c2d1205e6b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SignificantCostsRelatedToLegalAndEnvironmentalRemediationMatters_b1d19ef5-8033-455d-95f2-2dcbbe3063ec" xlink:href="pagp-20231231.xsd#pagp_SignificantCostsRelatedToLegalAndEnvironmentalRemediationMatters"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_SignificantCostsRelatedToLegalAndEnvironmentalRemediationMatters_b1d19ef5-8033-455d-95f2-2dcbbe3063ec" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_TransactionRelatedExpenses_908b41bd-f844-4868-9a57-f4a2bb5a16f2" xlink:href="pagp-20231231.xsd#pagp_TransactionRelatedExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_TransactionRelatedExpenses_908b41bd-f844-4868-9a57-f4a2bb5a16f2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_SegmentAmountsAttributableToNoncontrollingInterestsInConsolidatedJointVentures_eb15bd81-2d33-4e75-871b-cac9f8f9d728" xlink:href="pagp-20231231.xsd#pagp_SegmentAmountsAttributableToNoncontrollingInterestsInConsolidatedJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_SegmentAmountsAttributableToNoncontrollingInterestsInConsolidatedJointVentures_eb15bd81-2d33-4e75-871b-cac9f8f9d728" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_801de491-1fb1-45f1-bbd5-a10e701b13fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_801de491-1fb1-45f1-bbd5-a10e701b13fe" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_c4cf9882-c5fc-477a-a0b8-1ff74db6cd38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_c4cf9882-c5fc-477a-a0b8-1ff74db6cd38" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_fde26f2d-188d-425d-a788-cbec523c74e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_fde26f2d-188d-425d-a788-cbec523c74e7" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet_55d54d6c-cbd9-402e-a55f-310772a503f1" xlink:href="pagp-20231231.xsd#pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_pagp_GainsLossesOnInvestmentsInUnconsolidatedEntitiesNet_55d54d6c-cbd9-402e-a55f-310772a503f1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_d2c5a2d8-8dbd-44e1-b304-d49e6c658650" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_InterestExpense_d2c5a2d8-8dbd-44e1-b304-d49e6c658650" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_0e0aaba9-809a-4677-b071-654c6e9bd200" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_0e0aaba9-809a-4677-b071-654c6e9bd200" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_3854dfee-40a5-47ce-8d76-b97334de8f8f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_3854dfee-40a5-47ce-8d76-b97334de8f8f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_9e3bf2a5-7bb5-42a7-acb3-47e9ed6f9b37" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_9e3bf2a5-7bb5-42a7-acb3-47e9ed6f9b37" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_c18e3b67-0c04-45fa-8fde-f69a5f0888a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_ProfitLoss_c18e3b67-0c04-45fa-8fde-f69a5f0888a9" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_c638fe88-bea4-4ac2-8d09-ede171f612bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_c638fe88-bea4-4ac2-8d09-ede171f612bd" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_b7d37b3b-c18a-4e86-a4b1-6122a4044eea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedAbstract_244b2a2a-8c5e-4df7-859c-8988c70c6639" xlink:to="loc_us-gaap_NetIncomeLoss_b7d37b3b-c18a-4e86-a4b1-6122a4044eea" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.paalp.com/role/SegmentInformationGeographicalDataDetails" xlink:type="simple" xlink:href="pagp-20231231.xsd#SegmentInformationGeographicalDataDetails"/>
  <link:definitionLink xlink:role="http://www.paalp.com/role/SegmentInformationGeographicalDataDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_c877180a-eb43-4786-8d61-f58037597b1b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_9d90d887-bd21-4a29-8038-7419766c82f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_c877180a-eb43-4786-8d61-f58037597b1b" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_9d90d887-bd21-4a29-8038-7419766c82f5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_b92840cd-7cf1-4c6c-98fa-9c8607eedc62" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_9d90d887-bd21-4a29-8038-7419766c82f5" xlink:to="loc_srt_StatementGeographicalAxis_b92840cd-7cf1-4c6c-98fa-9c8607eedc62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_b92840cd-7cf1-4c6c-98fa-9c8607eedc62_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_b92840cd-7cf1-4c6c-98fa-9c8607eedc62" xlink:to="loc_srt_SegmentGeographicalDomain_b92840cd-7cf1-4c6c-98fa-9c8607eedc62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_91695051-d18b-4244-8ecc-1bde43d03892" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_b92840cd-7cf1-4c6c-98fa-9c8607eedc62" xlink:to="loc_srt_SegmentGeographicalDomain_91695051-d18b-4244-8ecc-1bde43d03892" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_3558afd6-296e-4bca-b895-8eff66db4dd4" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_91695051-d18b-4244-8ecc-1bde43d03892" xlink:to="loc_country_US_3558afd6-296e-4bca-b895-8eff66db4dd4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_f8591173-b932-4e95-933c-d10de2b62f3d" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_91695051-d18b-4244-8ecc-1bde43d03892" xlink:to="loc_country_CA_f8591173-b932-4e95-933c-d10de2b62f3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_a7b74565-b38a-4eda-9ac3-684d14c7eb1c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_c877180a-eb43-4786-8d61-f58037597b1b" xlink:to="loc_us-gaap_Revenues_a7b74565-b38a-4eda-9ac3-684d14c7eb1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_831b6547-c19a-4290-bc81-038940893ab9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_c877180a-eb43-4786-8d61-f58037597b1b" xlink:to="loc_us-gaap_NoncurrentAssets_831b6547-c19a-4290-bc81-038940893ab9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-roles-2023.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract" xlink:to="loc_us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
