Fassbender accepted the Coppa Volpi best actor trophy at a ceremony on Saturday (10Sep11) for his performance alongside Carey Mulligan in British director Steve McQueen's latest film.
Accepting his honour, Fassbender told the crowd, "It's just really nice when you take (a) chance and you do something that you think is relevant - you hope is relevant - and people respond the way they did."
But the festival's top prize - the Golden Lion - went to Russian filmmaker Alexander Sokurov for his take on Faust, about a scholar who sells his soul to the devil.
Black Swan director Darren Aronofsky, who served as head of the festival's jury, heaped praise on Sokurov as he presented him with the Golden Lion.
Aronofsky said, "There are some films that make you cry, there are some films that make you laugh, there are some films that change you forever after you see them; and this is one of them."