I started working at the age of 2, doing commercials and modeling in New York.

In 1979 McKeon was discovered by a casting director for The Facts of Life on the basis of her performance in a Hallmark greeting cards advertisement in which Nancy McKeon was able to cry on cue. From 2009 to 2010 McKeon appeared in a recurring role in the Disney Channel Original Series Sonny With a Chance as Connie Munroe the mother of Demi Lovato's title character. " In 1995 Nancy McKeon starred in her own series Can't Hurry Love which lasted one season.

She is best known for her role as Jo Polniaczek on the NBC sitcom The Facts of Life. Nancy Justine McKeon (born April 4 1966) is an American actress.