Melnick was born in Los Angeles, California. She graduated from San Fernando High School in Southern California's San Fernando Valley, and enrolled in college at age fifteen in the fall of 1999. Her first film appearance was in Disney's The Parent Trap. Since then, she has appeared in films such as Go and Orange County.
In 2000, Melnick and the rest of the Freaks and Geeks cast were nominated for the YoungStar Award for Best Young Ensemble Cast - Television, though the award ultimately went to Malcolm in the Middle.
Melnick is perhaps best known for her role as Cheerleader Cindy Sanders on Freaks and Geeks, whom central character Sam Weir (John Francis Daley) had a longtime crush on. She also had recurring roles on Boston Public, and Do Over. In 2001, she reunited with some of the cast members of Freaks and Geeks, appearing in the show Undeclared (which was also developed by Judd Apatow).
