Some of his notable films include: Doctor X (1932), I Am a Fugitive from a Chain Gang (1932), Annie Oakley (1935), The Last Days of Pompeii (also 1935), The Informer (1935) (as the head of the organization), and My Friend Flicka (1943).
He starred on the television drama, Waterfront (1954–1955), playing the role of Captain John Herrick. Foster has a star on the Hollywood Walk of Fame. He was sometimes credited in movies as Preston S. Foster. His first wife was stage actress Gertrude Warren (1926–1945; divorced). He had one daughter, Stephanie. He was married to his second wife, actress Sheila Darcy, from 1946 until his death.
During World War II while serving with the United States Coast Guard, he rose to the rank of Captain, Temporary Reserve. He eventually held the honorary rank of Commodore in the U.S. Coast Guard.
After the war and before his productive movie career, Foster became a singer of some note. In 1948, Foster created a trio with himself, Gene Leis and Foster’s wife, actress Sheila Darcy. Gene arranged the songs, and they played on radio and in clubs, appearing with Orrin Tucker, Peggy Ann Garner and Rita Hayworth.
He also guest starred on television, including the ABC drama series, Going My Way, starring Gene Kelly.