Edward Gargan was born of Irish parents in Brooklyn, New York in 1902. He was the elder brother of actor William Gargan whose July 17 birthday he shared.

Edward Gargan started as a musical comedy actor on Broadway. He sang in "Good News", "Rose-Marie", and other hit musicals of the 1920s, and also in opera. One of his early shows was "Polly of Hollywood" in 1927. He portrayed Patrolman Mulligan, one of the principals of "Strictly Dishonorable", in 1930.