Serie A - Inter confirm Forlan, loan Zarate
Forlan bid farewell to Atletico Madrid on Monday before travelling to Italy to finalise his move to Milan, and the 32-year-old has signed a two-year contract at the club.
Forlan, who played for Independiente, Manchester United and Villarreal before joining Atletico in 2007, said upon leaving the Spanish capital: "I see this new project as another great challenge. I leave a great club but I arrive to another top club.
"I know the Serie A as I have watched it on TV and I am happy to be able to play having already competed in La Liga and the Premier League.
"I loved (Inter's) project and their willingness to sign me."
Inter had earlier done some business on deadline day by releasing Colombian defender Nelson Rivas from the final year of his contract.
Rivas, 28, joined Inter from River Plate in 2007, but only made 28 appearances for the club in all competitions.
The versatile defender has spent the last two seasons out on loan, firstly at Livorno and then at Ukrainian club Dnipro.