José Ferrer played Romberg, with support from soprano Helen Traubel as a fictional character and Merle Oberon as actress, playwright, librettist, producer, and director Dorothy Donnelly.

The film, which takes its title from "Deep in My Heart, Dear," a song from The Student Prince, primarily consists of a series of cameo turns by nearly every significant singer or dancer on the MGM lot at the time.

These include dancer Cyd Charisse (dubbed by Carol Richards), Rosemary Clooney (Ferrer's wife), Vic Damone, Howard Keel, Gene Kelly and his brother Fred Kelly (their only on-screen appearance together), Tony Martin, Ann Miller, James Mitchell, Jane Powell, Joan Weldon, and the ballerina Tamara Toumanova (dubbed by Betty Wand).

Robert Easton, Russ Tamblyn, Susan Luckey, and Ludwig Stössel make uncredited appearances.

According to the reviewer for the New York Times, Deep in My Heart "calls for a strong digestive system and a considerable tolerance for clichés.