In 1949, Beymer began acting in television in a Los Angeles TV series for children Sandy Dreams (1949–53). He did it for three years, rehearsing after school during the week and recording it on Saturdays. The show ended when he was 13.
Beymer made his feature-film debut in Vittorio De Sica's Stazione Termini (1953). De Sica cast him in part because his dark complexion made him look like Jennifer Jones' nephew.