Fortier was born and raised in Pasadena, California. She was selected to be a Rose Princess in the 103rd Tournament of Roses Parade, which took place on January 1, 1992. She briefly studied at Saint Mary's College in Moraga, California, before moving to Los Angeles to pursue her acting career.
Fortier made her debut in the NBC teen comedy series Running the Halls in 1993, playing Holiday Friedman, one of the lead roles. In 1998 she was one of the leads on ABC's short-lived drama/soap opera Push, playing Gymnast and Olympic hopeful Cara Bradford.
Fortier appeared in the film To Gillian on Her 37th Birthday in 1996, playing the role of Cindy, the flirtatious best friend of Claire Danes' character. In 2000 she appeared in the comedy film Dean Quixote as Annie. The same year Fortier also appeared in the thriller film The In Crowd playing the role of Kelly who has a crush on the lead character, Brittany, played by Susan Ward; Fortier's portrayal elicited mildly positive notice from The New York Times reviewer Elvis Mitchell.
In 2013 Fortier joined the cast of the Netflix supernatural drama Hemlock Grove, playing the role of Marie Godfrey, one of the series' mortal characters.
