Gibson's role, which was first reported by the New York Post, was confirmed Tuesday by a person close to the production, who requested anonymity because he wasn't authorized to comment publicly on the matter. The film, a sequel to the 2009 hit comedy "The Hangover," is beginning production, with a release scheduled for May 2011.
Warner Bros., which is distributing the film, declined to comment.
Gibson might be hoping some comedy improves his tarnished reputation: a memorable appearance in the first "Hangover" film helped rehabilitate Mike Tyson's image.
Authorities are investigating claims by Gibson's ex-girlfriend Oksana Grigorieva that the 54-year-old actor-director physically abused her. Audio purportedly of Gibson making a series of racist and misogynistic rants was leaked earlier this year.
Before the audio leak, Gibson starred in the film "The Beaver." Though shooting on the film was completed in 2009, no release date has been announced by distributor Summit Entertainment.
"The Hangover 2" follows the characters of the first film on a trip to Southeast Asia for a wedding. The first "Hangover" grossed $462 million worldwide at the box office.