The son of a saloon keeper, Jack Benny (born Benny Kubelsky) began to study the violin at the age six, and his "ineptness" at it, would later become his trademark (in reality, he was a very accomplished player). When given the opportunity to play in live theatre professionally, Benny quit school and joined vaudeville. In the same theatre that Benny was working with were the very young The Marx Brothers. Their mother, Minnie Marx, wanted Benny to go on the road with them. However, this plan was foiled by his parents who would not let their 17-year-old son on the road.

Having a successful vaudeville career, Benny also had a greater career on radio for "The Jack Benny Program". The show was one of the few successful radio programs that also became a successful television show.

Benny also starred in several movies, including The Hollywood Revue of 1929 (1929), Broadway Melody of 1936 (1935), The Horn Blows at Midnight (1945) and George Washington Slept Here (1942), although he had much greater success on radio and on TV than he did on the big screen.

He was good friends with Fred Allen, with whom he had a long-standing comic "feud".