Tara Fitzgerald was born on September 18, 1967, Cuckfield, Sussex, England. She is the daughter of artist Michael Callaby and Irish portrait photographer Sarah Geraldine Fitzgerald.
She spent part of her childhood in the Bahamas, where her maternal grandfather ran a law firm. Her sister, Arabella, was born there. Following the family's return to England when she was three, Fitzgerald's parents separated, and her mother then married actor Norman Rodway. She has a half-sister from this marriage, Bianca Rodway. Her birth father, Callaby, died when she was 11. Her mother's aunt was actress Geraldine Fitzgerald; other cousins through the Fitzgerald family are the Irish novelist Jennifer Johnston and Irish actress Susan Fitzgerald.