Rosten was a successful Screenwriter. He wrote the story for The Dark Corner (1946), a film noir starring Mark Stevens; and Lured, the Douglas Sirk-directed period drama starring Charles Coburn; both films featured Lucille Ball. He is listed as one of the Writers for Captain Newman, M.D. (1963) adapted from his novel of the same title. Other films: Mechanized Patrolling (1943) (as Leonard Q. Ross), They Got Me Covered (1943) (story) (as Leonard Q. Ross), All Through the Night (1942) (story) (as Leonard Q. Ross), The Conspirators (1944) (screenplay), The Velvet Touch (1948), Sleep, My Love (1948) (novel) (screenplay), Double Dynamite (1954) (story), Walk East on Beacon (1952), and Mister Cory (1957) (story).