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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-04-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001273441</issuerCik>
        <issuerName>GRAN TIERRA ENERGY INC.</issuerName>
        <issuerTradingSymbol>GTE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001106191</rptOwnerCik>
            <rptOwnerName>GMT CAPITAL CORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>GMT CAPITAL CORP</rptOwnerStreet1>
            <rptOwnerStreet2>2300 WINDY RIDGE PARKWAY SUITE 550 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>ATLANTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30339</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000899037</rptOwnerCik>
            <rptOwnerName>BAY RESOURCE PARTNERS LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2300 WINDY RIDGE PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 550 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>ATLANTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30339</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001161416</rptOwnerCik>
            <rptOwnerName>BAY II RESOURCE PARTNERS LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2300 WINDY RIDGE PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 550 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>ATLANTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30339</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001733113</rptOwnerCik>
            <rptOwnerName>BAY RESOURCE PARTNERS OFFSHORE MASTER FUND, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2300 WINDY RIDGE PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 550 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>ATLANTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30339</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001075617</rptOwnerCik>
            <rptOwnerName>CLAUGUS THOMAS E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>GMT CAPITAL CORP</rptOwnerStreet1>
            <rptOwnerStreet2>2300 WINDY RIDGE PARKWAY SUITE 550 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>ATLANTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30339</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001396794</rptOwnerCik>
            <rptOwnerName>GMT Exploration Co LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1560 Broadway</rptOwnerStreet1>
            <rptOwnerStreet2>STE 2000</rptOwnerStreet2>
            <rptOwnerCity>Denver</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </securityTitle>
            <transactionDate>
                <value>2019-04-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>337400</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.46</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>74557386</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This Form 4 is being jointly filed by Bay Resource Partners, L.P. (Bay), a Delaware limited partnership, Bay II Resource Partners, L.P. (Bay II), a Delaware limited partnership, Bay Resource Partners Offshore Master Fund, L.P. (Bay Offshore), an exempted limited partnership organized under the laws of the Cayman Islands, GMT Exploration Company LLC (GMT Exploration), a Delaware limited liability company, GMT Capital Corp., a Georgia corporation (GMT Capital) on behalf of certain sub-advised accounts managed by it, and Thomas E. Claugus (Claugus), a United States citizen. The foregoing persons are hereinafter sometimes collectively referred to as the Reporting Persons.  Bay, Bay II, Bay Offshore, and Claugus, each have the dame address as the designated filer in Item 1 of this Form 4. GMT Exploration's address is 1560 Broadway, Suite 2000, Denver, Colorado 80202.</footnote>
        <footnote id="F2">GMT Capital is the general partner of Bay and Bay II and has the power to direct the affairs of Bay and Bay II, including voting and disposition of shares. As the discretionary investment manager of Bay Offshore, GMT Capital has power to direct voting and disposition of shares held by Bay Offshore and certain sub-advised accounts it manages. Claugus is the President of GMT Capital and in that capacity, directs the operations of each of Bay and Bay II and voting and disposition of shares held by Bay Offshore and certain sub-advised accounts. GMT Capital is also the non-discretionary manager of GMT Exploration through a separately managed account relationship. In addition, Claugus owns a controlling interest in GMT Exploration. GMT Capital and Claugus may be deemed to beneficially own indirect pecuniary interest as the result of performance-based fees and profit allocations.  Each of GMT Capital and Claugus disclaims such beneficial ownership except to the extent ultimately realized.</footnote>
        <footnote id="F3">The aggregate number of shares of common stock purchased on April 11, 2019, was 337,400 shares, at a price of $2.46 per share, resulting in an aggregate number of shares owned by the Reporting Persons of 74,557,386. Such shares were purchased, and thereafter beneficially owned by the Reporting Persons in the following amounts: Bay =105,200 shares purchased resulting in ownership of 20,830,990 shares; Bay II = 73,600 shares purchased resulting in ownership of 17,666,630 shares; Offshore Fund = 140,300 shares purchased resulting in ownership of 30,815,756 shares; GMT Capital = 3,500 shares purchased resulting in ownership of 853,510 shares; Claugus = 14,800 shares purchased resulting in ownership of 2,863,600 shares; GMT Exploration = 0 shares purchased resulting in ownership of 1,526,900 shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Philip J. Meyers</signatureName>
        <signatureDate>2019-04-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
