Hungarian club Gyori ETO have confirmed Estonia international Tarmo Kink has joined Middlesbrough on a three-year contract.
Kink has been discussing a move to The Riverside in recent weeks and was waiting to learn if Boro would push through a deal after passing a medical.
Boro have now paid €1million (£835,000) for the forward and will stump up a further €200,000 (£167,000) if the club win promotion to the Premier League.
The Championship side also have the option to extend Kink's contract by a further 12 months, with Gyor having negotiated a sell-on clause.
Kink is due to bid farewell to Gyor during half-time of Thursday's Europa League tie against Montpellier before linking up with Boro in time for the new season.
Gyor's general director Tibor Klement told Nemzeti Sport: "We have terminated Tarmo Kink's contract with Gyor by mutual consent so the striker can move to England.
"His price is €1million which must be paid within 14 days. Boro must pay an additional €200,000 if they win promotion with Kink in their squad.
"If they sell the player, a quarter of the fee must be paid to ETO.
"Kink has signed a three-year contract, with the option of one more year and the extension depends on Middlesbrough's decision."