Once a Sinner is a 1931 American pre-Code romance film directed by Guthrie McClintic and written by George Middleton. The film stars Dorothy Mackaill, Joel McCrea, John Halliday, C. Henry Gordon, Ilka Chase and Sally Blane. The film was released on January 25, 1931, by Fox Film Corporation. As of January 2026, the film is preserved by the UCLA Film & Television Archive.