Lawrence's career began as a child photographer's model. She appeared in her first film, Billy Rose's Diamond Horseshoe (1945), as a night-club patron. A year later, she made a strong impression in her second film at 20th Century-Fox, Margie, in which she played outgoing flapper Maryville.
In January 1947, she married John Forrest Fontaine, an actor known professionally as Jeffrey Stone. This was kept secret until June 28, 1947, when Lawrence's mother threw her daughter a church wedding in Beverly Hills, but the marriage ended with a divorce granted on September 28, 1949.
In 1951, she wed Johnny Murphy; the couple had two children before divorcing in 1957. After marrying Lester R. Nelson in 1961, she had two more children. She made several more television appearances in 1962, then retired from acting altogether. She and Nelson divorced in 1976.
Upon moving to MGM, Lawrence appeared with Gig Young in the 3D movie Arena (1953) and in Her Twelve Men with Greer Garson. She played the role of Gertie Cummings in the film version of Oklahoma!, in which she gets into a knockdown catfight with Gloria Grahame ("Ado Annie"). In 1957, she starred in Kronos with Jeff Morrow. Although the science-fiction film was not praised by critics at the time, it eventually attracted a cult following for its imaginative storyline and special effects.
Between 1958 and 1962, Lawrence made four guest appearances on Perry Mason. In 1958, she played Ellen Waring in "The Half-Wakened Wife" and Gloria Barton in "The Case of the Jilted Jockey." In 1961, she played a murderess in "The Case of the Envious Editor", and in 1962, she played Agnes Theilman in "The Case of the Shapely Shadow".
Lawrence has a star at 1735 Vine Street in the Television section of the Hollywood Walk of Fame. It was dedicated on February 8, 1960.
Barbara Lawrence died of kidney failure on November 13, 2013, aged 83, in Los Angeles, California, but her death was not reported until January 3, 2014.