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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-10-23</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>2019-10-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>419700</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.14</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>77590386</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F4"/>
            </securityTitle>
            <transactionDate>
                <value>2019-10-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>307200</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.14</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>77897586</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F5"/>
            </securityTitle>
            <transactionDate>
                <value>2019-11-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>753491</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.3</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>78651077</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F6"/>
            </securityTitle>
            <transactionDate>
                <value>2019-11-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1035700</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.07</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>79686777</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F7"/>
            </securityTitle>
            <transactionDate>
                <value>2019-11-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>287709</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.05</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>79974486</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.</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 October 23, 2019, was 419,700 shares, at a price of $1.14 per share, resulting in an aggregate number of shares owned by the Reporting Persons of 77,590,386. Such shares were purchased, and thereafter beneficially owned by the Reporting Persons in the following amounts: Bay = 153,700 shares purchased resulting in ownership of 21,810,090 shares; Bay II = 97,500 shares purchased resulting in ownership of 18,332,930 shares; Offshore Fund = 150,900 shares purchased resulting in ownership of 32,048,456 shares; GMT Capital = 2,100  shares purchased resulting in ownership of 879,610  shares; Claugus = 15,500 shares purchased resulting in ownership of 2,992,400 shares; GMT Exploration = 0 shares purchased resulting in ownership of 1,526,900 shares.</footnote>
        <footnote id="F4">The aggregate number of shares of common stock purchased on October 24, 2019, was 307,200 shares, at a price of $1.14 per share, resulting in an aggregate number of shares owned by the Reporting Persons of 77,897,586. Such shares were purchased, and thereafter beneficially owned by the Reporting Persons in the following amounts: Bay = 112,400 shares purchased resulting in ownership of 21,992,490 shares; Bay II = 71,300 shares purchased resulting in ownership of 18,404,230 shares; Offshore Fund = 110,500 shares purchased resulting in ownership of 32,158,956 shares; GMT Capital = 1,600  shares purchased resulting in ownership of 881,210  shares; Claugus = 11,400 shares purchased resulting in ownership of 3,003,800 shares; GMT Exploration = 0 shares purchased resulting in ownership of 1,526,900 shares.</footnote>
        <footnote id="F5">The aggregate number of shares of common stock purchased on November 6, 2019, was 753,491 shares, at a price of $1.30 per share, resulting in an aggregate number of shares owned by the Reporting Persons of 78,651,077. Such shares were purchased, and thereafter beneficially owned by the Reporting Persons in the following amounts: Bay = 275,891 shares purchased resulting in ownership of 22,198,381 shares; Bay II = 175,000 shares purchased resulting in ownership of 18,579,230 shares; Offshore Fund = 270,900 shares purchased resulting in ownership of 32,429,856 shares; GMT Capital = 3,800  shares purchased resulting in ownership of 885,010  shares; Claugus = 27,900 shares purchased resulting in ownership of 3,031,700 shares; GMT Exploration = 0 shares purchased resulting in ownership of 1,526,900 shares.</footnote>
        <footnote id="F6">The aggregate number of shares of common stock purchased on November 7, 2019, was 1,035,700 shares, at a price of $1.07 per share, resulting in an aggregate number of shares owned by the Reporting Persons of 79,686,777. Such shares were purchased, and thereafter beneficially owned by the Reporting Persons in the following amounts: Bay = 379,200 shares purchased resulting in ownership of 22,577,581 shares; Bay II = 240,600 shares purchased resulting in ownership of 18,819,830 shares; Offshore Fund = 372,400 shares purchased resulting in ownership of 32,802,256 shares; GMT Capital = 5,200  shares purchased resulting in ownership of 890,210  shares; Claugus = 38,300 shares purchased resulting in ownership of 3,070,000 shares; GMT Exploration = 0 shares purchased resulting in ownership of 1,526,900 shares.</footnote>
        <footnote id="F7">The aggregate number of shares of common stock purchased on November 8 2019, was 287,709 shares, at a price of $1.05 per share, resulting in an aggregate number of shares owned by the Reporting Persons of 79,974,486. Such shares were purchased, and thereafter beneficially owned by the Reporting Persons in the following amounts: Bay = 105,209 shares purchased resulting in ownership of 22,682,790 shares; Bay II = 66,800 shares purchased resulting in ownership of 18,886,630 shares; Offshore Fund = 103,500 shares purchased resulting in ownership of 32,905,756 shares; GMT Capital = 1,500  shares purchased resulting in ownership of 891,710 shares; Claugus = 10,700 shares purchased resulting in ownership of 3,080,700 shares; GMT Exploration = 0 shares purchased resulting in ownership of 1,526,900 shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Philip J. Meyers</signatureName>
        <signatureDate>2019-09-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
