The comedy focuses on three roommates - played by Adam Devine, Blake Anderson and Anders Holm - who are trying to transition from college into adulthood.
Willis will play a seemingly friendly drug dealer who proves to be unexpectedly ruthless, Entertainment Weekly reports.
Willis, the eldest daughter of Bruce Willis and Demi Moore, made her screen debut in 1995 alongside her mother in Now and Then.
She has since appeared in several movies, including The House Bunny and Sorority Row.
Willis most recently had a guest stint on 90210, playing a love interest for Jessica Lowndes's character.
