Two years later, he started working at Craftsman Labs in New York from 1920 to 1923 and shortly for Goldwyn Pictures in Culver City, California in 1923. After his time at Goldwyn Pictures, Biroc returned to New York and took a job as film printer for Famous Players-Lasky, where he was shortly after promoted to assistant cameraman. After Famous Players-Lasky shut down in 1927, Biroc moved to Los Angeles to work for United Artists prior to moving to RKO to work as a camera operator. Biroc started at RKO by serving as assistant to cinematographers Leo Tover, Robert De Grasse, and Edward Cronjager. During his time at RKO, Biroc worked on "Cimarron" (1931), "Swing Time" (1936), and "Shall We Dance" (1937). He also worked on "A Woman Rebels" (1936), "Sylvia Scarlett" (1935), and "Five Came Back" (1939) (among others), but received no screen credit as RKO hardly credited camera operators. His last work before World War II was for "Bombardier" (1943).