Leachman will play the owner of the erotic bookstore that is the only place that Amy Anderson, an aspiring young writer, can get a job.
Adult World's script is by Andrew Cochran. The cast will also feature John Cusack, Evan Peters, and Emma Roberts.
Leachman's stage credits include As You Like It, South Pacific, A Story for a Sunday Evening (which earned her a Theater World Award), The Crucible, Sunday Breakfast, and King of Hearts, as well as her one-woman show, Cloris.
Her film and television credits include Young Frankenstein, The Mary Tyler Moore Show, and Dancing with the Stars. She is also the author of the autobiography Cloris.