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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e21ab-f0e8-7997-90ae-9abc4786c631,g:0430a3d1-d589-4bec-9509-e1ada19bfe7b-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:oke="http://www.oneok.com/20260630" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2024-01-31" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.oneok.com/20260630">
  <xs:import namespace="http://fasb.org/srt/2026" schemaLocation="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2026" schemaLocation="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2024-01-31" schemaLocation="https://www.xbrl.org/dtr/type/2024-01-31/types.xsd"/>
  <xs:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2026" schemaLocation="https://xbrl.sec.gov/dei/2026/dei-2026.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/ecd/2026" schemaLocation="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="oke-20260630_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="oke-20260630_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="oke-20260630_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="oke-20260630_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="CoverPage" roleURI="http://www.oneok.com/role/CoverPage">
        <link:definition>0000001 - Document - Cover Page</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFINCOME" roleURI="http://www.oneok.com/role/CONSOLIDATEDSTATEMENTSOFINCOME">
        <link:definition>9952151 - Statement - CONSOLIDATED STATEMENTS OF INCOME</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFINCOMEParenthetical" roleURI="http://www.oneok.com/role/CONSOLIDATEDSTATEMENTSOFINCOMEParenthetical">
        <link:definition>9952152 - Statement - CONSOLIDATED STATEMENTS OF INCOME (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME" roleURI="http://www.oneok.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME">
        <link:definition>9952153 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEParenthetical" roleURI="http://www.oneok.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEParenthetical">
        <link:definition>9952154 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDBALANCESHEETS" roleURI="http://www.oneok.com/role/CONSOLIDATEDBALANCESHEETS">
        <link:definition>9952155 - Statement - CONSOLIDATED BALANCE SHEETS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDBALANCESHEETSParenthetical" roleURI="http://www.oneok.com/role/CONSOLIDATEDBALANCESHEETSParenthetical">
        <link:definition>9952156 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCASHFLOWS" roleURI="http://www.oneok.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS">
        <link:definition>9952157 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCASHFLOWSParenthetical" roleURI="http://www.oneok.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWSParenthetical">
        <link:definition>9952158 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITYANDREDEEMABLENONCONTROLLINGINTERESTS" roleURI="http://www.oneok.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITYANDREDEEMABLENONCONTROLLINGINTERESTS">
        <link:definition>9952159 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY AND REDEEMABLE NONCONTROLLING INTERESTS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITYANDREDEEMABLENONCONTROLLINGINTERESTSParenthetical" roleURI="http://www.oneok.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITYANDREDEEMABLENONCONTROLLINGINTERESTSParenthetical">
        <link:definition>9952160 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY AND REDEEMABLE NONCONTROLLING INTERESTS (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES" roleURI="http://www.oneok.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES">
        <link:definition>9952161 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FAIRVALUEMEASUREMENTS" roleURI="http://www.oneok.com/role/FAIRVALUEMEASUREMENTS">
        <link:definition>9952162 - Disclosure - FAIR VALUE MEASUREMENTS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVES" roleURI="http://www.oneok.com/role/RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVES">
        <link:definition>9952163 - Disclosure - RISK-MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DEBT" roleURI="http://www.oneok.com/role/DEBT">
        <link:definition>9952164 - Disclosure - DEBT</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EQUITY" roleURI="http://www.oneok.com/role/EQUITY">
        <link:definition>9952165 - Disclosure - EQUITY</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="VARIABLEINTERESTENTITIES" roleURI="http://www.oneok.com/role/VARIABLEINTERESTENTITIES">
        <link:definition>9952166 - Disclosure - VARIABLE INTEREST ENTITIES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EARNINGSPERSHARE" roleURI="http://www.oneok.com/role/EARNINGSPERSHARE">
        <link:definition>9952167 - Disclosure - EARNINGS PER SHARE</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="UNCONSOLIDATEDAFFILIATES" roleURI="http://www.oneok.com/role/UNCONSOLIDATEDAFFILIATES">
        <link:definition>9952168 - Disclosure - UNCONSOLIDATED AFFILIATES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="COMMITMENTSANDCONTINGENCIES" roleURI="http://www.oneok.com/role/COMMITMENTSANDCONTINGENCIES">
        <link:definition>9952169 - Disclosure - COMMITMENTS AND CONTINGENCIES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUES" roleURI="http://www.oneok.com/role/REVENUES">
        <link:definition>9952170 - Disclosure - REVENUES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTS" roleURI="http://www.oneok.com/role/SEGMENTS">
        <link:definition>9952171 - Disclosure - SEGMENTS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies" roleURI="http://www.oneok.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies">
        <link:definition>9955511 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FAIRVALUEMEASUREMENTSTables" roleURI="http://www.oneok.com/role/FAIRVALUEMEASUREMENTSTables">
        <link:definition>9955512 - Disclosure - FAIR VALUE MEASUREMENTS (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESTables" roleURI="http://www.oneok.com/role/RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESTables">
        <link:definition>9955513 - Disclosure - RISK-MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="VARIABLEINTERESTENTITIESTables" roleURI="http://www.oneok.com/role/VARIABLEINTERESTENTITIESTables">
        <link:definition>9955514 - Disclosure - VARIABLE INTEREST ENTITIES (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EARNINGSPERSHARETables" roleURI="http://www.oneok.com/role/EARNINGSPERSHARETables">
        <link:definition>9955515 - Disclosure - EARNINGS PER SHARE (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="UNCONSOLIDATEDAFFILIATESTables" roleURI="http://www.oneok.com/role/UNCONSOLIDATEDAFFILIATESTables">
        <link:definition>9955516 - Disclosure - UNCONSOLIDATED AFFILIATES (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUESTables" roleURI="http://www.oneok.com/role/REVENUESTables">
        <link:definition>9955517 - Disclosure - REVENUES (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTSTables" roleURI="http://www.oneok.com/role/SEGMENTSTables">
        <link:definition>9955518 - Disclosure - SEGMENTS (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FAIRVALUEMEASUREMENTSScheduleofRecurringFairValueMeasurementsDetails" roleURI="http://www.oneok.com/role/FAIRVALUEMEASUREMENTSScheduleofRecurringFairValueMeasurementsDetails">
        <link:definition>9955519 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of Recurring Fair Value Measurements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FAIRVALUEMEASUREMENTSScheduleofRecurringFairValueMeasurementsDetails_1" roleURI="http://www.oneok.com/role/FAIRVALUEMEASUREMENTSScheduleofRecurringFairValueMeasurementsDetails_1">
        <link:definition>9955519 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of Recurring Fair Value Measurements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FAIRVALUEMEASUREMENTSNarrativeDetails" roleURI="http://www.oneok.com/role/FAIRVALUEMEASUREMENTSNarrativeDetails">
        <link:definition>9955520 - Disclosure - FAIR VALUE MEASUREMENTS - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESNarrativeDetails" roleURI="http://www.oneok.com/role/RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESNarrativeDetails">
        <link:definition>9955521 - Disclosure - RISK-MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofFairValueofDerivativeInstrumentsDetails" roleURI="http://www.oneok.com/role/RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofFairValueofDerivativeInstrumentsDetails">
        <link:definition>9955522 - Disclosure - RISK-MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Schedule of Fair Value of Derivative Instruments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofFairValueofDerivativeInstrumentsDetails_1" roleURI="http://www.oneok.com/role/RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofFairValueofDerivativeInstrumentsDetails_1">
        <link:definition>9955522 - Disclosure - RISK-MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Schedule of Fair Value of Derivative Instruments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofNotionalQuantitiesforDerivativeInstrumentsDetails" roleURI="http://www.oneok.com/role/RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofNotionalQuantitiesforDerivativeInstrumentsDetails">
        <link:definition>9955523 - Disclosure - RISK-MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Schedule of Notional Quantities for Derivative Instruments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofCashFlowHedgesDetails" roleURI="http://www.oneok.com/role/RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofCashFlowHedgesDetails">
        <link:definition>9955524 - Disclosure - RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Schedule of Cash Flow Hedges (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofCashFlowHedgesDetails_1" roleURI="http://www.oneok.com/role/RISKMANAGEMENTANDHEDGINGACTIVITIESUSINGDERIVATIVESScheduleofCashFlowHedgesDetails_1">
        <link:definition>9955524 - Disclosure - RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Schedule of Cash Flow Hedges (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DEBTDetails" roleURI="http://www.oneok.com/role/DEBTDetails">
        <link:definition>9955525 - Disclosure - DEBT (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EQUITYDetails" roleURI="http://www.oneok.com/role/EQUITYDetails">
        <link:definition>9955526 - Disclosure - EQUITY (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="VARIABLEINTERESTENTITIESDetails" roleURI="http://www.oneok.com/role/VARIABLEINTERESTENTITIESDetails">
        <link:definition>9955527 - Disclosure - VARIABLE INTEREST ENTITIES (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EARNINGSPERSHAREDetails" roleURI="http://www.oneok.com/role/EARNINGSPERSHAREDetails">
        <link:definition>9955528 - Disclosure - EARNINGS PER SHARE (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="UNCONSOLIDATEDAFFILIATESScheduleofEquityinNetEarningsfromInvestmentsDetails" roleURI="http://www.oneok.com/role/UNCONSOLIDATEDAFFILIATESScheduleofEquityinNetEarningsfromInvestmentsDetails">
        <link:definition>9955529 - Disclosure - UNCONSOLIDATED AFFILIATES - Schedule of Equity in Net Earnings from Investments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="UNCONSOLIDATEDAFFILIATESNarrativeDetails" roleURI="http://www.oneok.com/role/UNCONSOLIDATEDAFFILIATESNarrativeDetails">
        <link:definition>9955530 - Disclosure - UNCONSOLIDATED AFFILIATES - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUESDetails" roleURI="http://www.oneok.com/role/REVENUESDetails">
        <link:definition>9955531 - Disclosure - REVENUES (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUESDetails_1" roleURI="http://www.oneok.com/role/REVENUESDetails_1">
        <link:definition>9955531 - Disclosure - REVENUES (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTSScheduleofOperatingSegmentsFinancialInformationDetails" roleURI="http://www.oneok.com/role/SEGMENTSScheduleofOperatingSegmentsFinancialInformationDetails">
        <link:definition>9955532 - Disclosure - SEGMENTS - Schedule of Operating Segments Financial Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTSScheduleofReconciliationsforSegmentsDetails" roleURI="http://www.oneok.com/role/SEGMENTSScheduleofReconciliationsforSegmentsDetails">
        <link:definition>9955533 - Disclosure - SEGMENTS - Schedule of Reconciliations for Segments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTSScheduleofReconciliationofNetIncometoTotalSegmentAdjustedEBITDADetails" roleURI="http://www.oneok.com/role/SEGMENTSScheduleofReconciliationofNetIncometoTotalSegmentAdjustedEBITDADetails">
        <link:definition>9955534 - Disclosure - SEGMENTS - Schedule of Reconciliation of Net Income to Total Segment Adjusted EBITDA (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="oke_CommoditySalesMember" abstract="true" name="CommoditySalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_ServicesMember" abstract="true" name="ServicesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_InvestmentsAndOtherAssetsAbstract" abstract="true" name="InvestmentsAndOtherAssetsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="oke_TermLoanAgreementMember" abstract="true" name="TermLoanAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_MinorityInterestIncreaseFromContributionsByNoncontrollingInterestHolders" abstract="false" name="MinorityInterestIncreaseFromContributionsByNoncontrollingInterestHolders" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="oke_DerivativeCollateralRighttoReclaimCashTotal" abstract="false" name="DerivativeCollateralRighttoReclaimCashTotal" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="oke_DerivativesByCommodityAxis" abstract="true" name="DerivativesByCommodityAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="oke_DerivativesByCommodityDomain" abstract="true" name="DerivativesByCommodityDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_DerivativePositonByTransactionTypeAxis" abstract="true" name="DerivativePositonByTransactionTypeAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="oke_TransactionTypeDomain" abstract="true" name="TransactionTypeDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_SellorMember" abstract="true" name="SellorMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_PurchasorMember" abstract="true" name="PurchasorMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_DerivativeInstrumentByMethodForSettingNotionalAmountAxis" abstract="true" name="DerivativeInstrumentByMethodForSettingNotionalAmountAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="oke_DerivativeInstrumentByMethodForSettingNotionalAmountDomain" abstract="true" name="DerivativeInstrumentByMethodForSettingNotionalAmountDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_FixedPriceMember" abstract="true" name="FixedPriceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_BasisMember" abstract="true" name="BasisMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_SwingSwapsMember" abstract="true" name="SwingSwapsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_FuturesAndSwapsMember" abstract="true" name="FuturesAndSwapsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_A5.55NotesPayableDue2026Member" abstract="true" name="A5.55NotesPayableDue2026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_A3.5BillionCreditAgreementMember" abstract="true" name="A3.5BillionCreditAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_A4.85SeniorNotesDueJuly2026Member" abstract="true" name="A4.85SeniorNotesDueJuly2026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_DebtInstrumentCovenantIndebtednessToAdjustedEBITDAMaximumFromAcquisitions" abstract="false" name="DebtInstrumentCovenantIndebtednessToAdjustedEBITDAMaximumFromAcquisitions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="oke_IndebtednesstoAdjustedEBITDAMaximum" abstract="false" name="IndebtednesstoAdjustedEBITDAMaximum" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="oke_IndebtednessToAdjustedEbitdaCurrent" abstract="false" name="IndebtednessToAdjustedEbitdaCurrent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="oke_DebtInstrumentNumberOfBorrowingsWithin90DaysOfClosingDateMaximum" abstract="false" name="DebtInstrumentNumberOfBorrowingsWithin90DaysOfClosingDateMaximum" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="oke_DebtInstrumentPeriodFollowingClosingForBorrowings" abstract="false" name="DebtInstrumentPeriodFollowingClosingForBorrowings" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="oke_BasicEPSfromContinuingOperationsAbstract" abstract="true" name="BasicEPSfromContinuingOperationsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="oke_DilutedEPSfromContinuingOperationsAbstract" abstract="true" name="DilutedEPSfromContinuingOperationsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="oke_NorthernBorderPipelineMember" abstract="true" name="NorthernBorderPipelineMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_OverlandPassPipelineCompanyMember" abstract="true" name="OverlandPassPipelineCompanyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_MatterhornMember" abstract="true" name="MatterhornMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_SaddlehornMember" abstract="true" name="SaddlehornMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_RoadrunnerGasTransmissionMember" abstract="true" name="RoadrunnerGasTransmissionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_BridgeTexMember" abstract="true" name="BridgeTexMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_PowderSpringsMember" abstract="true" name="PowderSpringsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_OtherUnconsolidatedAffiliateMember" abstract="true" name="OtherUnconsolidatedAffiliateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_TexasCityLogisticsMember" abstract="true" name="TexasCityLogisticsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_EigerMember" abstract="true" name="EigerMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_PowderSpringsLogisticsLLCMember" abstract="true" name="PowderSpringsLogisticsLLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_RevenuePerformanceObligationRemainingPeriod" abstract="false" name="RevenuePerformanceObligationRemainingPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="oke_LiquidsCommodityMember" abstract="true" name="LiquidsCommodityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_ResidueNaturalGasSalesMember" abstract="true" name="ResidueNaturalGasSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_ExchangeServicesAndNaturalGasGatheringAndProcessingRevenueMember" abstract="true" name="ExchangeServicesAndNaturalGasGatheringAndProcessingRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_TransportationandStorageRevenueMember" abstract="true" name="TransportationandStorageRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_OtherMember" abstract="true" name="OtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_NaturalGasGatheringAndProcessingMember" abstract="true" name="NaturalGasGatheringAndProcessingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_NaturalGasLiquidsMember" abstract="true" name="NaturalGasLiquidsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_WhollyOwnedInterstateNaturalGasPipelinesMember" abstract="true" name="WhollyOwnedInterstateNaturalGasPipelinesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_RefinedProductsAndCrudeOilMember" abstract="true" name="RefinedProductsAndCrudeOilMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_IntersegmentRevenuesbyNameAxis" abstract="true" name="IntersegmentRevenuesbyNameAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="oke_IntersegmentRevenuesByNameDomain" abstract="true" name="IntersegmentRevenuesByNameDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_NaturalGasGatheringandProcessingIntersegmentMember" abstract="true" name="NaturalGasGatheringandProcessingIntersegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_AdjustedEBITDAUnconsolidatedAffiliates" abstract="false" name="AdjustedEBITDAUnconsolidatedAffiliates" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="oke_AdjustedEBITDA" abstract="false" name="AdjustedEBITDA" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="oke_EliminationsAndReconcilingItemsMember" abstract="true" name="EliminationsAndReconcilingItemsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_EnLinkAcquisitionMember" abstract="true" name="EnLinkAcquisitionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_TransactionCostsAxis" abstract="true" name="TransactionCostsAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="oke_TransactionCostsDomain" abstract="true" name="TransactionCostsDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_AdvisoryFeesAndSeveranceMember" abstract="true" name="AdvisoryFeesAndSeveranceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_NoncashCompensationExpenseMember" abstract="true" name="NoncashCompensationExpenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="oke_OtherCorporateCostsandNoncashItems" abstract="false" name="OtherCorporateCostsandNoncashItems" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
