Corbett was born in 1945 in Camp Sherman, Oregon to Henry Ladd Corbett, Jr. and Katherine Minahen (née Coney) "Kay" Corbett. She is a great-great-granddaughter of Oregon pioneer and Senator Henry W. Corbett. She studied drama at Pittsburgh's Carnegie Tech before its merger with the Mellon Institute of Industrial Research to form Carnegie Mellon University in 1967.

One of Corbett's first television roles was on ABC's short-lived police detective show, N.Y.P.D., in 1968. In an episode called The Case of the Shady Lady, Corbett played a Dancer who tries to make her husband's suicide into a murder for the insurance money. She had supporting roles in Out of It with Jon Voight (1969), and as a mute in Let's Scare Jessica to Death (1971).

In 1973, Corbett moved to Los Angeles under contract to Universal Studios, as one of the last contract players. Her first role under contract was an episode of the detective series Kojak: Conspiracy of Fear in 1973. She had recurring roles on Marcus Welby, M.D., Otherworld, Ellery Queen, and Love Is a Many Splendored Thing, and guest roles on such series as Wonder Woman, Emergency!, Barnaby Jones, Hawaii Five-O, Columbo: An Exercise in Fatality, Gunsmoke, McMillan & Wife, Barbary Coast, Banacek, One Day at a Time, Family, Otherworld, Murder, She Wrote, Cheers, and Magnum, P.I.

In 1974 Corbett joined the cast of NBC's The Rockford Files where she played Beth Davenport, the beleaguered Lawyer and sometimes lover of series lead Jim Rockford, a private investigator portrayed by James Garner. Corbett left the series at the end of the fourth season over a dispute between the show's producers and Universal, who owned Corbett's contract as a contract player. Corbett went on to do more TV work, eventually returning to play Davenport again in the Rockford Files TV movies of the 1990s.

In the 2000s, Corbett served as Artistic Director of the Haven Project, a theatre project for underprivileged children in Portland, Oregon, a replication of New York's 52nd St. Project.

She worked in many regional theatres, including the Long Wharf Theatre, the Berkshire Theatre Festival, the Eugene O'Neill Festival, Seattle Repertory Theatre, and the Repertory Theatre of New Orleans. In 2014, she directed the production "Bo-Nita" at Portland Center Stage.