As an actor he was a leading man in early talkies and also appeared in Welles' final film, The Other Side of the Wind.

He tried a number of theatrical agencies before getting stage work including The Barker (1927, New York; 1928, London) in which he appeared opposite future wife Claudette Colbert.

He co-wrote and directed the "My Friend Bonito" segment of Orson Welles's unfinished Pan-American anthology film It's All True (1941).

[7]: 155 Some of Foster's other directorial efforts include Kiss the Blood off My Hands (1948), Rachel and the Stranger (1948), Woman on the Run (1950) and The Sign of Zorro (1958).

These verses later appeared in the Disney Sing-Along Songs version of the Zorro Theme in its 1987 direct-to-video episode, "Heigh-Ho".