Braff turned to his fans and Kickstarter to fund the film in order to get funding without making creative sacrifices.
Patinkin will play Braff's father in the film, according to the Hollywood Reporter. Braff and his brother, Adam Braff, wrote the script together.
The film will follow the life of a 35-year-old struggling actor, father and husband trying to figure out his role in each part of his life.
Patinkin currently stars in "Homeland" and has previously played in "The Princess Bride," "Ragtime" and "Dick Tracy."
He joins Jim Parsons of "The Big Bang Theory," who was cast earlier this month.