Born in Missouri, Warrick lived and worked in New York City as a young woman. She first gained fame in Hollywood when she starred opposite Orson Welles in the 1941 film classic Citizen Kane, and she went on to appear in such movies as The Corsican Brothers, Journey Into Fear, and The Great Bank Robbery. She made her Broadway debut in the short-lived play Miss Lonelyhearts (1957) and also starred in the musicals Take Me Along (1959) and Irene (1973) in addition to touring as Anna in The King and I. Warrick's regional theater credits include Who's Afraid of Virginia Woolf? and Long Day's Journey Into Night.
Her television credits include As the World Turns and Peyton Place, but she is probably best known for her work as matriarch Phoebe Tyler Wallingford on the long-running ABC daytime drama All My Children; she appeared on the first episode in 1970 and recently revisited the show to commemorate its 35th anniversary. Warrick's autobiography, The Confessions of Phoebe Tyler, was published in 1980.
Warrick received the first national Arts in Education Award in 1983 for her leadership in making the arts more central to the schooling process. (The award was later renamed the Ruth Warrick Award for Arts in Education and is now given annually.) She was also a metaphysical teacher licensed by Unity School of Practical Christianity in Lees Summit, Missouri. Warrick is survived by three children, a grandson, and three great-grandchildren.