Collins is set to play the movie's villain, Mr. Harter, who will team up with Vergara to adopt the stooges.
The movie cast will also include previously announced "Glee" star Jane Lynch, who will play Mother Superior, the nun who runs the Catholic orphanage where the trio grew up. The three stooges will be played by Tony Award nominee Sean Hayes (Larry), Chris Diamantopoulos (Moe) and Will Sasso (Curly).
Peter and Bobby Farrelly are set to direct the film.
Collins' Broadway credits include Monty Python's Spamalot, The Loves of Anatol, The Ritz and Moonchildren. Vergara, best known for her role as Gloria Delgado-Pritchett on the ABC series "Modern Family," has performed on Broadway in Chicago.
A release date for the film has not yet been announced.