Born Rona Berstein to a Jewish family in New York, New York, she was diagnosed with a rare form of muscular dystrophy at age 9. When she was 13, she became the nationwide coordinator of singer Eddie Fisher's fan clubs. Her date for the high school prom was singer Steve Lawrence. She majored in pre-law at college, until her uncle, a judge, advised her to switch to journalism.

Barrett became a gossip columnist for the Bell-McClure newspaper syndicate in 1957. In 1966, she began broadcasting Hollywood gossip on the Los Angeles television station ABC. She appeared on TV regularly, going on to appear on ABC's five owned and operated stations around the country. Not everyone was thrilled with the arrangement. WABC-TV in New York put her pre-recorded gossip segment into its nightly local news, but anchor Roger Grimsby would generally introduce it by scowling and insulting Barrett. Still, Barrett's inclusion was a surefire way to boost ratings. Barrett made the enemies list of Frank Sinatra by criticizing his personal life, particularly his relationships with his children.

She developed the first in-depth personal TV specials about the celebrities of motion pictures, television, music, sports and politics, and had a series of magazines on the entertainment industry that were top-rated at newsstands, including Rona Barrett's Hollywood. As such she paved the way for Barbara Walters and many entertainment reporters.

Barrett has had one husband, Bill Trowbridge; they were married on September 22, 1973 and remained so until his death on December 7, 2001.

In 1972, her novel titled The Lovo-maniacs was published. Her autobiography, Miss Rona, was published in 1974. It memorably began: "Just an inch, Miss Rona, just let me put it in an inch!" as a famous-but-unnamed movie star pleaded to be allowed to experience a modicum of sexual intercourse with her. In the book she also acknowledged having a nose job. She wrote two other books, How You Can Look Rich and Achieve Sexual Ecstasy (1978) and The Man Who Will Be King, Unauthorized Biography of Prince Charles (1980).

Barrett began appearing on Good Morning America in 1975. She was signed in 1981 to co-star with Tom Snyder on NBC's Tomorrow, but dropped out before the first show was completed. In 1986, she bought a ranch at Santa Ynez, California, and began commuting back and forth to Los Angeles. In 1991, she retired full time to her ranch, where she began planting fields of lavender.

She found marketing lavender flowers was not so easy and decided Paul Newman had the right idea with his successful Newman's Own products. She then founded the Rona Barrett Lavender Company offering lavender-based skin care, gourmet food, and aromatherapy products. She also started The Rona Barrett Foundation, a non-profit organization dedicated to the aid and support of senior citizens in need that is supported by a 2 ortion of the profits from her lavender business.

Rona Barrett continues to reside in Santa Ynez with her three dogs and two cats.