Nancy McKeon was born in Westbury, New York to Don and Barbara McKeon, began modeling baby clothes for the Sears catalogue at the age of two and she and her brother did over sixty-five commercials in seven years. She appeared briefly on the soap operas "The Secret Storm", and "Another World". When her brother, Philip McKeon won a role on the TV series, "Alice", the family moved to Los Angeles.

Her first real acting break came when she did the short-lived TV series "Stone" and guested on "Starsky and Hutch". The producers of "The Facts of Life" were so impressed by Nancy's performance as the street-wise girl in a pilot called "Dusty", they decided to sign her to play Jo on "The Facts of Life". Nancy has starred in the television movies, "High School U.S.A.", "Poison Ivy", "This Child Is Mine" and "The Greater Alarm". She provided the voices for animated shows like "Puppy's Great Adventure".
Was cast as the lead in the TV show Working Girl, but left before production started. She was replaced by Sandra Bullock. Dated Michael J. Fox Sister of Philip McKeon. Declined to participate in The Facts of Life Reunion because, "I'm just not a fan of that kind of thing. I would not watch it, so why would I be IN it? It's just never the same." She did, however, offer to direct a movie which would have dealt with the girls reuniting after Jo's death. Practices a form of martial arts. Directed a short film and an episode of her series, The Division. Was considered for the part of Monica on Friends. The role later went to Courteney Cox. Gave birth to her first child, daughter Aurora, was born on March 6, 2004. Lived, for a time, in Kansas City, Missouri. Has one daughter named Aurora. Was number 81 on vh1's 100 Greatest Kid Stars At age 40, she is expecting her second child. No due date has been announced. (October 16, 2006).