Lautaro Martinez has completed a move to Inter from Racing Club for a reported fee of €22.7 million (£20m/$26.4m), the Italian club has confirmed.
The 20-year-old striker arrived in Milan at the end of May to complete a medical and has now signed a five-year contract with Luciano Spalletti's team.
The Argentina international had been the subject of an offer from Real Madrid and was courted by Atletico Madrid, but a switch to Inter had been imminent for months, as the player himself revealed in March .
Martinez scored 13 goals in 21 appearances for Racing in Argentina's Primera Division this season, earning his international debut for La Albiceleste as a substitute in the 6-1 friendly loss to Spain in March.
A statement on Inter's official website said: "Lautaro Martinez is officially an Inter player. The Argentine forward has signed a contract with the club that runs until 30 June 2023."
As expected, Martinez missed out on a place in Jorge Sampaoli's squad for the World Cup finals in Russia.
But the exciting young attacker can look forward to life in Italy's top flight next term after finalising his deal with Inter, who secured a return to the Champions League by finishing fourth in Spalletti's first campaign in charge.
Atletico had been considered the frontrunners to secure Martinez's services, but Diego Simeone’s side incurred the wrath of Racing after allegedly subjecting the player to an unauthorised medical last year.
Martinez has been likened to Manchester City star Sergio Aguero by former Inter and Argentina star Hernan Crespo , who expects him to fit in well alongside Mauro Icardi.
"He is very good and can play in many roles; on the wing, as a secondary striker or up top by himself as the main striker," he said in March. “He has knack for scoring and he's an intelligent guy.
"Coming to Inter isn't easy, he'll need to be helped and protected. Then hopefully he can show all of his qualities from the beginning, but it won't be a disaster if he needs a little time to settle in.
"He can play with Icardi, I don't think there will be any problems. He reminds me a little bit of Aguero in some ways, like with his low centre of gravity, but he's Lautaro Martinez."
He becomes Inter's fifth signing of what is turning into a busy summer for the Nerazzurri.
They have already brought in Roma midfielder Radja Nainggolan , Lazio defender Stefan de Vrij, Juventus full-back Kwadwo Asamoah and Sassuolo forward Matteo Politano and as they prepare to return to the Champions League in 2018-19.