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  <headerData>
    <submissionType>13F-HR</submissionType>
    <filerInfo>
      <liveTestFlag>LIVE</liveTestFlag>
      <flags/>
      <filer>
        <credentials>
          <cik>0001504103</cik>
          <ccc>XXXXXXXX</ccc>
        </credentials>
      </filer>
      <periodOfReport>06-30-2022</periodOfReport>
    </filerInfo>
  </headerData>
  <formData>
    <coverPage>
      <reportCalendarOrQuarter>06-30-2022</reportCalendarOrQuarter>
      <isAmendment>false</isAmendment>
      <filingManager>
        <name>ENCAP ENERGY CAPITAL FUND VIII, L.P.</name>
        <address>
          <ns1:street1>9651 Katy Freeway</ns1:street1>
          <ns1:street2>Suite 600</ns1:street2>
          <ns1:city>Houston</ns1:city>
          <ns1:stateOrCountry>TX</ns1:stateOrCountry>
          <ns1:zipCode>77024</ns1:zipCode>
        </address>
      </filingManager>
      <reportType>13F HOLDINGS REPORT</reportType>
      <form13FFileNumber>028-17796</form13FFileNumber>
      <provideInfoForInstruction5>Y</provideInfoForInstruction5>
      <additionalInformation>EnCap Partners GP, LLC ("EnCap Partners GP") is the sole general partner of EnCap Partners, LP, which is the managing member of EnCap Investments Holdings, LLC, which is the sole member of EnCap Investments GP, L.L.C., which is the general partner of EnCap Investments L.P., which is the general partner of EnCap Equity Fund VIII GP, L.P., which is the sole general partner of EnCap Energy Capital Fund VIII, L.P. Therefore, EnCap Partners GP may be deemed to share the right to direct the disposition of the securities held by EnCap Energy Capital Fund VIII, L.P.</additionalInformation>
    </coverPage>
    <signatureBlock>
      <name>Douglas E. Swanson, Jr.</name>
      <title>Managing Partner of GP of Reporting Manager</title>
      <phone>713.659.6100</phone>
      <signature>/s/ Douglas E. Swanson, Jr.</signature>
      <city>Houston</city>
      <stateOrCountry>TX</stateOrCountry>
      <signatureDate>08-10-2022</signatureDate>
    </signatureBlock>
    <summaryPage>
      <otherIncludedManagersCount>1</otherIncludedManagersCount>
      <tableEntryTotal>3</tableEntryTotal>
      <tableValueTotal>161846</tableValueTotal>
      <isConfidentialOmitted>false</isConfidentialOmitted>
      <otherManagers2Info>
        <otherManager2>
          <sequenceNumber>1</sequenceNumber>
          <otherManager>
            <form13FFileNumber>028-18569</form13FFileNumber>
            <name>EnCap Partners GP, LLC</name>
          </otherManager>
        </otherManager2>
      </otherManagers2Info>
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