Born in New York City, Leonard Gershe made his Broadway debut as a lyricist for the 1950 revue Alive and Kicking. He wrote the book for Harold Rome's musical stage adaptation of Destry Rides Again in 1959, and in 1969 a play, Butterflies are Free. Later Gershe wrote another play, Snacks.
He wrote the lyrics for the "Born in a Trunk" sequence from the Judy Garland/James Mason musical A Star Is Born. In the 1950s, Gershe wrote ten scripts for the Ann Sothern sitcom Private Secretary. He also wrote a number of episodes of The Lucy Show. His screen credits include Funny Face, 40 Carats, and Butterflies Are Free.