The experienced attacker joined the Giuseppe Meazza side from Atletico Madrid in the summer of 2011, but failed to make an impact in Serie A as he netted only twice in 18 league appearances.
Therefore, Forlan opted to move on again as he signed a three-year deal with Internacional on Friday, and he has reflected on his time in Milan with little fondness.
"I was playing in a position where I had never played before. I accepted it because I had no other choice. I'm here now, though, and I hope to play in my natural position as striker again," Forlan told reporters.
Forlan previously wore the jerseys of Independiente, Manchester United and Villarreal.