"FC Internazionale Milano can confirm that an agreement has been reached to extend Lautaro Martinez's contract. The 1997-born forward has put pen to paper on a deal lasting until 30 June 2029," said Inter in a statement.
Argentina striker Lautaro will reportedly earn a net salary of nine million euros per season after renewing a deal which was set to expire in two years' time.
Inter president Giuseppe Marotta said last month that Lautaro had already agreed to sign his new contract but that the club would wait until he returned from post-Copa America holidays to announce it.
Lautaro was key to Argentina retaining the Copa America, netting five times including the only goal in the final triumph over Colombia.
International glory for the 26-year-old came after he helped power Inter to their second Serie A title in four seasons, finishing their triumphant campaign a whopping 19 points ahead of local rivals AC Milan.
The Inter skipper topped the scoring charts with 24 goals in 33 league appearances, eight strikes ahead of his nearest rival Dusan Vlahovic.
Lautaro confirming his intention to stay at Inter is a huge boost for a club which headed into the close season in an uncertain mood after a sudden change in ownership.
Investment fund Oaktree took control of Inter just days after they won their 20th league crown when previous owners Suning defaulted on repayment of a loan which matured at 395 million euros.
However, Oaktree have opted for continuity rather than revolution since ousting ex-president Steven Zhang and Chinese conglomerate Suning, under whom Inter won seven trophies, including two Serie A titles, and reached two European finals.
Coach Simone Inzaghi extended his contract with Inter to 2026 this month, while star midfielder Nicolo Barella signed a new deal until 2029 ahead of Euro 2024.
Inter begin their league title defence at Genoa on Saturday.
