Nixon started her career at the age of 14, appearing in Little Darlings. Around that time, she also started appearing on plays on Broadway and Off-Broadway. In 1981, she won the Theatre World Award for her performance in The Philadelphia Story.
In 1984, while a freshman in college, Nixon appeared simulaneously in two Mike Nichols-directed hit Broadway plays: Tom Stoppard's The Real Thing and David Rabe's Hurlyburly. In each performance, Nixon appeared as "Donna" in the first act of Hurlyburly at the Ethel Barrymore Theatre, then walked to the Plymouth Theatre, changed costumes and performed one scene as "Debbie" in The Real Thing opposite Jeremy Irons and Christine Baranski. Then, Nixon changed her costume again and returned to the Ethel Barrymore Theatre to resume her performance as "Donna." In the interest of fairness to other actors, Actors' Equity Association no longer permits one actor to perform in two shows simultaneously.
Nixon's other Broadway credits include The Heidi Chronicles (1989-90), Angels in America (1993-94), The Last Night of Ballyhoo (1997-98), The Women (2001-02) and Who's Afraid of Virginia Woolf?. For her participation in the latter, she earned a Los Angeles Drama Critics Award.
Nixon has been nominated at various times for awards and critically praised for her characterization of Miranda in Sex and the City during its six-season run, finally winning a primetime Emmy in 2004 for Best Supporting Actress in a Comedy Series.
In September 2004, it was reported that despite previous long-term relationships with men, she had been in a nearly year-long relationship with a woman, education expert Christine Marinoni. When asked about this, she neither denied or confirmed, instead stating that "My private life is private. But at the same time, I have nothing to hide. So what I will say is that I am very happy."
Nixon has two children, daughter Samantha (b. 1996) and son Charles (b. 2002). Their father is Danny Mozes, an English professor, with whom Nixon had a 15-year relationship. She has used her public profile as an advocate for better public schools in New York, one of which her daughter attends.
It was reported in the NY Post on February 27, 2005 that Cynthia Nixon has moved in with her partner, Christine Marinoni. Nixon was previously splitting time between the house on the Upper West Side she shared with Mozes and Marinoni's ground-floor apartment in Park Slope. But now she and the kids will be full-time Brooklynites.
- Nixon on Gay Marriage Crusade Contactmusic.com, 2005-03-05.
Her filmography/television resume is as follows:
- Sex and the City (from 1998 to 2003)
- Kiss Kiss, Dahlings/The Last Mile (2002)
- Advice From a Caterpillar (2001)
- Papa's Angels (2000)
- Marvin's Room (1996, alongside Leonardo DiCaprio)
- Baby's Day Out (1994), as the baby's nanny
- Tanner '88 (1988, television series)
- The Manhattan Project (1986)
- O.C. and Stiggs
- Amadeus (1984)
- My Body, my Child (1982, miniseries, with future Sex and...co star Sarah Jessica Parker)
- Prince of the City (1981)
- Little Darlings (1980)