Barnes also has appeared in films, including A Vacation in Hell (1979), Licence to Kill (1989), Stepfather III (1992), The Crossing Guard (1995), Mallrats (1995), The Devil's Rejects (2005) and The Visitation (2006).

Barnes was born in Fort Dix, New Jersey,[1] the third of four children of a father who was a major in the United States Air Force and a mother who was a homemaker.

[1] Barnes' first break came when Bob Hope saw her in a local fashion show and invited her to join his troupe for a 1973 performance at Walter Reed Army Medical Center in Washington, D.C. She subsequently moved to Los Angeles to pursue a career in showbusiness.

While working as a hostess at a Hollywood nightclub, Barnes posed nude for the "Pet of the Month" photo layout in the March 1976 issue of Penthouse magazine under the pseudonym Joann Witty.

[2] In 1976, Barnes began studying acting with coach Sal Dano, whose students included Tom Selleck, Robert Hays and Catherine Bach.

[1] In 1981, Barnes was cast as Terri Alden on the ABC sitcom Three's Company after Jenilee Harrison served as interim replacement to Suzanne Somers, who had left the series as a result of contractual dispute with producers.

She revealed that after shooting the first few episodes, she felt "uncomfortable" on the set, mostly because of tension among the cast members, and unsuccessfully petitioned the producers to release her from her contract.

After Three's Company was canceled by ABC in 1984, Barnes accepted guest-starring roles on television shows such as Hotel, Murder, She Wrote and Highway to Heaven.

In 1992, she starred in the NBC television movie Perry Mason and the Case of the Reckless Romeo with Raymond Burr and in the horror film Stepfather III.

[9] In 2014, Barnes was cast in a recurring role as Magda Andel, the mother of Petra (played by Yael Grobglas), in the CW comedy-drama series Jane the Virgin.