A Missouri-born actress, singer and author, she is best known for creating the beloved Eloise children's series. She also served as musical arranger for The Ziegfeld Follies and The Harvey Girls and performed with a group of backup singers in the 1930s on the Chesterfield Radio Program.
She worked in her younger years as a singer and choral director for radio programs such as The Bing Crosby-Woodbury Show. In 1943, she became a vocal arranger for MGM.
She played the role of fashion editor Maggie Prescott in the film musical, Funny Face.
She was married for two years to jazz trombonist, Jack Jenney. In 1942, she wed her second husband, William Spier, whom she divorced five years later.
She worked as a vocal coach and musical arranger for Judy Garland and other prominent performers. Garland's daughter, Liza Minnelli, was Thompson's goddaughter and the inspiration for her Eloise books.