At the age of 10, she became the youngest person ever to win a competitive Academy Award, for her performance as Addie Loggins in Paper Moon co-starring her father, Ryan O'Neal.

She later starred in the films The Bad News Bears, Nickelodeon, and Little Darlings, and appeared in guest roles in the television series Sex and the City, 8 Simple Rules, and Law & Order: Criminal Intent.

O'Neal's mother died of lung cancer at age 63, after a career in which she appeared in such movies as Walk on the Wild Side and Follow That Dream.

In her 2010 appearance on RuPaul's Drag Race, O'Neal stated that her father had not attended the Academy Awards ceremony with her due to his busy schedule.

[8] O'Neal starred in films such as The Bad News Bears (1976) with Walter Matthau, International Velvet (1978) with Christopher Plummer and Anthony Hopkins, and Little Darlings (1980) with Kristy McNichol, and co-starred in Nickelodeon (1976) with her father and in Circle of Two (1980) with Richard Burton.

In the early 2000s, O'Neal returned to acting with guest appearances in Sex and the City, 8 Simple Rules for Dating My Teenage Daughter, and Law & Order: Criminal Intent.

In January 2006, she participated in the second season of ABC's reality series Dancing with the Stars with professional partner Nick Kosovich.

The movie, directed by Valerio Zanoli, stars Karen Grassle and five Academy Award winners: O'Neal, Cloris Leachman, Louis Gossett Jr., George Chakiris, and Olympia Dukakis.

[12] O'Neal's relationship with tennis player John McEnroe began in 1984 when she moved into his Central Park West apartment in New York City.

[20] On July 2, 2008, O'Neal pleaded guilty to disorderly conduct in connection with the arrest and agreed to spend two half-day sessions in a drug treatment program.

'"[23] In 2011, O'Neal wrote a new collection of memoirs, Found: A Daughter's Journey Home, which dealt with her tempestuous relationship with her father, volatile marriage to McEnroe, and recent drug arrest.