She was born in Saint Joseph, Missouri in 1916 (as per her son and the 1930 U.S. census, dated April 3, 1930, which gives her age as 13 as of that date). Her parents were Fred R. & Annie L. Warrick. By writing an essay in high school called “Prevention and Cure of Tuberculosis”, Warrick won a contest to be Miss Jubilesta, Missouri’s paid ambassador to New York City. She began her career in the 1940s as a radio singer where she met her first husband Eric Rolf, but her first big break was being hired by a young Orson Welles for Citizen Kane, where she played Emily Monroe Norton. Welles hired her again for Journey into Fear. She appeared in The Corsican Brothers, The Iron Major, Mr. Winkle Goes to War, and Guest in the House. Following World War II, she had a role in the Academy Award winning Disney film Song of the South; she also appeared in Daisy Kenyon, which starred Joan Crawford and Henry Fonda, but by the late 1940s her film roles were becoming infrequent and less notable. After playing Betty Hutton’s sister-in-law in Let’s Dance, she starred as a troubled wife looking back at her life in the religious drama Second Chance and an alcoholic wife and mother in One Too Many. In the 1950s, she befriended soap opera executives Irna Phillips and Agnes Nixon. Warrick became a cast member on the soap opera The Guiding Light, playing Janet Johnson, R.N. from 1953–54. Phillips was impressed by Warrick’s performance and hired her for her new soap opera, As the World Turns when the show debuted in 1956. Her character, Edith Hughes, was madly in love with a married man, Jim Lowell. Phillips wanted the characters to live happily ever after, but Procter & Gamble, which owned the show, demanded that the characters not endorse adultery, so Jim “died”. She stayed on the show until 1960.

From 1959-60, she understudied for Una Merkel and (future All My Children co-star) Eileen Herlie in the Broadway musical, Take Me Along. During the 1961-62 television season, she starred in Father of the Bride television series. Then, in 1965, she joined the cast of the primetime serial, Peyton Place, playing Hannah Cord. While there had been previous primetime serials (such as One Man’s Family), none had enjoyed the phenomenal success of Peyton Place. Warrick received an Emmy Award nomination for her work on this show in 1967, the same year she left the show. In 1969, she made her last major film, Disney’s The Great Bank Robbery. During this time, Nixon had been moving up the daytime television ranks. She had created her own show, One Life to Live, in 1968. ABC approved her new show, All My Children, in 1969. When All My Children debuted on January 5, 1970, Warrick was among the contracted cast, playing Pine Valley’s imperious matriarch Phoebe Tyler (the character’s full name via her marriages would eventually be Phoebe English Tyler Wallingford Matthews Wallingford). The show was an instant hit and Phoebe became a popular character. While her role was originally that of a serious society snob concerned mainly with keeping her family’s name at the top of the town’s social register, she later began to add much humor into the role, especially when her character, separated from her husband of many years, began having an affair with a phony professor Langley Wallingford, and eventually married him. Warrick received Daytime Emmy Award nominations in 1975 and 1977. In 1985, she played Hannah Cord in the television film Peyton Place: The Next Generation.

Due to health problems, actor Louis Edmonds, who portrayed Warrick’s All My Children husband, left the show in 1995. Combined with Warrick’s own health problems, that signaled a reduction in her screen time in the 1990s. Warrick broke her hip while on vacation in Greece in 2001 and thenceforth used a wheelchair. She had a brief re-emergance in 2002 when Phoebe made a return appearance at a hospital board meeting and later attended a society function with niece Brooke. Ruth was seen rarely on screen until All My Children’s 35th anniversary show on January 5, 2005. This would be Warrick’s final screen appearance. When she was wheeled into the building, the cast and crew gave her a standing ovation to welcome her back after such a long absence. This episode featured not only a rare appearance from Warrick, but the return of her stepdaughter Verla, played by Carol Burnett. In 1971 she published a single with the song 41,000 Plus 4 The Ballad of the Kent State Massacre as an hommage to Sandra Lee Scheuer, William Knox Schroeder, Jeffrey Glenn Miller and Allison Beth Krause, the four students killed at Kent State University during a demonstration against the Vietnam war. She published her autobiography, The Confessions of Phoebe Tyler (co-written by Don Preston) in 1980, the same year she won a Soapy Award (a prelude to the Soap Opera Digest Awards). She received a Star on the Hollywood Walk of Fame and was on hand to receive her Daytime Emmy Award for Lifetime Achievement in 2004. Warrick was a member of the Democratic Party, working with the administrations of John F. Kennedy, Lyndon Johnson and Jimmy Carter on labor and education issues. Upon Carter’s 1980 defeat, she sent him a long letter thanking him for his efforts. He replied, telling her that if he had hired her as a speechwriter, he would have been reelected. Warrick had generally liberal political views. In her first years at All My Children, Warrick was flustered by her character’s conservative politics and support of U.S. involvement in the Vietnam War, which Warrick strongly opposed. In July 2000, she refused to accept a lifetime achievement award from the South Carolina Arts Commission because she was offended by legislators’ decision to move the Confederate flag from the state Capitol dome to another spot on the grounds in response to a boycott of the state by flag opponents. A lifelong supporter of African-American rights, she felt the flag should be removed completely, and commented, “In my view, this was no compromise. It was a deliberate affront to the African-Americans, who see it as a sign of oppression and hate”. In her senior years, she became a spokeswoman for the rights of senior citizens as well as the disabled and was appointed to the U.N. World Women’s Committee on Mental Health. She died of complications related to pneumonia on January 15, 2005, aged 88. She received a memorial tribute at the 11th annual Screen Actors Guild Awards. She was interred at the Church of the Transfiguration.