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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-02-28</periodOfReport>

    <issuer>
        <issuerCik>0001319229</issuerCik>
        <issuerName>TransMontaigne Partners L.P.</issuerName>
        <issuerTradingSymbol>TLP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001496587</rptOwnerCik>
            <rptOwnerName>Majors Ronald A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>TRANSMONTAIGNE</rptOwnerStreet1>
            <rptOwnerStreet2>1670 BROADWAY, SUITE 3100</rptOwnerStreet2>
            <rptOwnerCity>DENVER</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2011-02-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>524.52</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Units Representing Limited Partner Interest</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>524.52</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1311.3</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each phantom unit represents the right to receive one common unit of TLP, or the cash value thereof.</footnote>
        <footnote id="F2">Represents the portion of the 2011 award granted under the Amended and Restated Savings and Retention Plan (the &quot;Plan&quot;) by the Compensation Committee of the Board of Directors of TransMontaigne Inc. (the &quot;Plan Administrator&quot;) that the Reporting Person elected to be invested in &quot;phantom units,&quot; as if invested in an investment fund that tracks the financial performance of the common units of TLP.   The award allocations were approved by the Plan Administrator on February 28, 2011 and were allocated to the phantom units after the close of the market on such date.</footnote>
        <footnote id="F3">Phantom units awarded under the Plan vest 50% as of the January 1 that falls closest to the second anniversary of the grant date, with the remaining 50% vesting as of the January 1 that falls closest to the third anniversary of the grant date.  The phantom units are subject to earlier vesting upon achieving certain age or service thresholds as defined in the Plan. Upon vesting, phantom units may be paid out, in the sole discretion of the Plan Administrator, in cash or in common units of TLP, or a combination thereof.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Ronald A. Majors</signatureName>
        <signatureDate>2011-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
