As an actress, Ann Hearn is best known for her film roles as Sally Fraser in The Accused, Stella in My Father the Hero, Loretta Muscatine in Lorenzo's Oil, Mrs. Perlili in Mirror Mirror, the teacher in Josh and S.A.M. and Linda in Nobody's Fool. She also played Mrs. Russell in Debating Robert Lee, Constance in Frankie and Johnny Are Married and Professor Tracey in The War at Home.

Television credits include portraying Margaret Fouch on Evening Shade and Andrea Fordham on St. Elsewhere. She also starred in the made-for-television movies The Dollmaker, Deadly Care, Why on Earth? and The Final Days. She guest starred on Rizzoli & Isles, Big Love, Numb3rs, Judging Amy, Crisis Center, ER, The Client, Murder, She Wrote and Jack's Place.

On stage, she appeared in Dreams of the Washer King (Theatre 40); and portrayed Irina in Three Sisters (Los Angeles Theatre).