Rowlands was born on June 19, 1930, in Madison, Wisconsin. Her mother, Mary Allen (Neal), was a housewife who later worked as an actress under the stage name Lady Rowlands. Her father, Edwin Myrwyn Rowlands, was a banker and state legislator. He was a member of the Wisconsin Progressive Party, and was of Welsh descent. She had a brother, David Rowlands.\n', '
Her family moved to Washington, D.C., in 1939, when Edwin was appointed to a position in the United States Department of Agriculture; moved to Milwaukee, Wisconsin, in 1942, when he was appointed as branch manager of the Office of Price Administration; and later moved to Minneapolis, Minnesota. From 1947–50, she attended the University of Wisconsin, where she was a popular student already renowned for her beauty. While in college, she was a member of Kappa Kappa Gamma. She left for New York City to study drama at the American Academy of Dramatic Arts.\n', '
In the early 1950s, Rowlands performed with repertory theatre companies and at the Provincetown Playhouse. She made her Broadway debut in The Seven Year Itch and toured in a national production of the play. Rowlands costarred with Paul Stewart in the 26-episode syndicated TV series Top Secret (1954–55), and she guest starred on such anthology television series as Robert Montgomery Presents, Appointment with Adventure, Kraft Television Theatre, and Studio One (1955). In 1956, she starred in Middle of the Night opposite Edward G. Robinson. She appeared alongside her husband John Cassavetes on an episode ("Fly Baby, Fly") of the 1959–60 NBC detective series Johnny Staccato. She also appeared on an episode of the NBC western series, Riverboat, starring Darren McGavin, and the ABC adventure series, The Islanders, set in the South Pacific. Also in 1959, Rowlands appeared in the Western series Laramie episode titled "Run to Tumavaca". Rowlands made her film debut in The High Cost of Loving in 1958.\n', '