<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-09-14</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001392091</issuerCik>
        <issuerName>Blueknight Energy Partners, L.P.</issuerName>
        <issuerTradingSymbol>BKEP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001143380</rptOwnerCik>
            <rptOwnerName>ERGON INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 1639</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>JACKSON</rptOwnerCity>
            <rptOwnerState>MS</rptOwnerState>
            <rptOwnerZipCode>39215-1639</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001687635</rptOwnerCik>
            <rptOwnerName>Ergon Asphalt &amp; Emulsions, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 1639</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>JACKSON</rptOwnerCity>
            <rptOwnerState>MS</rptOwnerState>
            <rptOwnerZipCode>39215-1639</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series A Preferred Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-09-14</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2488789</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.46</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Units</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2488789</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20801757</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Series A Preferred Units have no expiration date and are convertible at any time, in whole or in part, on, subject to adjustment, a one-for-one basis into Common Units representing limited partner interests of the Issuer at the holder's election as set forth in the Fourth Amended and Restated Agreement of Limited Partnership of the Issuer, dated September 14, 2011 and filed with the Securities and Exchange Commission as Exhibit 3.1 to the Issuer's Current Report on Form 8-K filed on September 14, 2011.</footnote>
        <footnote id="F2">This Form 4 is being filed jointly by Ergon, Inc. (&quot;Ergon&quot;) and Ergon Asphalt &amp; Emulsions, Inc. (&quot;EA&amp;E&quot;). Ergon directly owns 100% of the outstanding ownership interests of EA&amp;E, and may therefore be deemed to beneficially own the securities of the Issuer owned directly by EA&amp;E.</footnote>
    </footnotes>

    <remarks>Blueknight Energy Partners G.P., L.L.C., a Delaware limited liability company and the general partner of the Issuer (the &quot;General Partner&quot;), has sole responsibility for conducting the business of and managing the operations of the Issuer. Blueknight GP Holding, LLC, a Delaware limited liability company and the sole member of the General Partner (&quot;Holdings&quot;), has the right to appoint all of the directors of the General Partner. EA&amp;E (and therefore, Ergon) is the indirect parent of Holdings, and may therefore be deemed a director by deputization.</remarks>

    <ownerSignature>
        <signatureName>/s/ Emmitte J. Haddox, President and Chief Executive Officer of Ergon, Inc.</signatureName>
        <signatureDate>2020-09-16</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ J. Baxter Burns, II, President of Ergon Asphalt &amp; Emulsions, Inc.</signatureName>
        <signatureDate>2020-09-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
