Gilbert is best remembered for the lyrics to the Oscar-winning song "Zip-a-Dee-Doo-Dah" from the film Song of the South
, which he wrote with Allie Wrubel
in 1947. He also wrote American English lyrics for the songs in The Three Caballeros
featuring Donald Duck. He also wrote the Andy Williams' 1965 hit, "...and Roses and Roses", and "Lost in Your Love" with Sidney Miller, to music by Bert Jay.
He married actress Janis Paige in 1962.