Carpenter was born in Las Vegas, Nevada, where she attended Bishop Gorman High School. At 15, the family moved to Rosarito B.C., Mexico, and then to Chula Vista (a suburb of San Diego) where she attended Chula Vista High and Bonita Vista High. After graduation, she was a San Diego Chargers cheerleader in 1991 before beginning her Hollywood career. She had also dabbled in sky-diving. She married Damian Hardy on October 5, 2002 and she gave birth to son Donavan Charles Hardy on March 24, 2003.
Carpenter was discovered by a commercial agent when she was a waitress. This led to several roles on TV advertisements. She made guest appearances in Baywatch and Miss Match, and she has had a role in Malibu Shores. Her best known role was that of Cordelia on TV's Buffy the Vampire Slayer and Angel. She is one of the only cast members from Buffy and Angel who refuses to charge for her autograph at fan conventions.
After 7 years playing Cordelia Chase, 3 years on Buffy the Vampire Slayer and 4 years on Angel, Charisma was not invited back as a regular for Angel's fifth and final season. She agreed to return for the 100th episode although she wasn't asked until Sarah Michelle Gellar turned down the chance to guest star in the episode.
She also had a recurring role as a psychic demon called The Seer in the popular witch drama Charmed, appearing in three episodes.
Carpenter modeled nude for the June 2004 issue of Playboy magazine. She made the decision to pose as a way to motivate herself to lose her pregnancy weight. The photos were taken ten months after she gave birth to her son.
Carpenter had a recurring role as Kendall Casablancas in the TV series Veronica Mars for the 2005-2006 season.
Charisma recently starred in Voodoo Moon by writer/director Kevin VanHook, as well as an assortment of made-for-television movies. One such recent movie was called Relative Chaos on ABC Family, costarring with Nicholas Brendon, one of her costars from Buffy the Vampire Slayer.