Born July 15, 1916, in Louisville, Kentucky, Colt attended Yale's school of design with the intention of becoming a set designer. After moving to New York, he worked a series of odd jobs in summer theater and ballet companies that sparked an interest in costuming.
In 1944, Colt's designs debuted on Broadway in the Leonard Bernstein-Adolph Greene-Betty Comden musical On the Town.The success of 1950's Guys and Dolls heralded Colt's most celebrated period. In 1956, he earned three Tonys nominations for Pipe Dream, The Lark and Phoenix '55, and won for Pipe Dream. Colt scored two more nominations in 1957 Lil' Abner, The Sleeping Prince and another in 1960 for Greenwillow. In all, he designed costumes for 88 Broadway shows. His work has also appeared in movies Lil' Abner, Stiletto, Top Banana and on television Kiss Me Kate, The Adams Chronicles, The Enchanted Nutcracker, in addition to more than 15 shows for Off-Broadway's Phoenix Theatre.