Franco appeared on Tuesday's edition of the faux news program to promote his new film "Oz the Great and Powerful."
Asked by the show's host if he also acts in plays, Franco told Colbert: "I'm going to. We're going to do 'Of Mice and Men' on Broadway. There's a character Slim, we haven't cast it yet. You could do it."
Franco said he will play George in the Great Depression-set drama, which was last staged on Broadway in 1974.