Director Todd Phillips' dark drama Joker about the origins of the villainous character won the Golden Lion award at the Venice Film Festival on Saturday.
Joaquin Phoenix, who won rave reviews from critics at the festival, plays Batman's nemesis, and follows his transformation from a vulnerable loner into the confident villain.
Roman Polanski's military drama An Officer And A Spy took the runner-up Silver Lion Grand Jury Prize.
Meanwhile, Italian actor Luca Marinelli won the best actor award for his portrayal of a poor, aspiring writer in Martin Eden.
Taking the best actress award was French actress Ariane Ascaride, who was recognised for her role in Gloria Mundi. She plays a mother desperate to help her financially-strapped family in this drama set in Marseilles.
Hong Kong born director Yonfan received the award for best screenplay for the fantasy animation No 7 Cherry Lane, set in 1967 Hong Kong.
(Reporting by Marie-Louise Gumuchian; editing by Jason Neely)