A native of Long Beach, California, she spent her early life in Los Angeles and Mexico City, raised by her widowed father.While working as a model in San Francisco, she met and married John Phillips in 1962, and went on to co-found the vocal group the Mamas and the Papas in 1965.Between the ages of six and twelve, Phillips and her sister were raised in Mexico City, Mexico, where her father was studying sociology on the GI Bill at Mexico City College.
She co-wrote some of the band's hits, including California Dreamin', which appears on their debut album If You Can Believe Your Eyes and Ears (1966).
Recording of the Mamas and the Papas' second album (eponymously titled The Mamas and the Papas (1966) and sometimes referred to as Cass, John, Michelle, Dennie, whose names appear thus above the band's name on the cover) was interrupted when Michelle Phillips became indiscreet about her affair with Gene Clark of the Byrds.
After Phillips' reinstatement, the band embarked on a brief tour of the East coast, playing a series of precarious shows in Washington, D.
C., Baltimore, Maryland, and at Fordham University in New York City.
Phillips became a main cast member on the series Knots Landing from 1987 to 1993, portraying Anne Matheson, the mother of Paige Matheson (portrayed by Nicollette Sheridan).