Christian's first role on television was a guest appearance on Dallas, followed by a series regular role as Melody Hughes on the short-lived drama Berrenger's. She left her breakthrough role as Babylon 5's Susan Ivanova unexpectedly following the fourth season, when contract negotiations for the fifth and final season — aggravated by the possibility that there would not be one — broke down. J. Michael Straczynski, the series' creator, maintains that she chose to leave on her own. (Her appearance in the series finale was filmed during the fourth season.) Before Babylon 5, Christian performed feature film roles such as a stripper possessed by an alien serial killer in The Hidden (1987), a police department psychologist Susan Riley in Maniac Cop 2 and as model Hexina in Hexed (1993). She posed nude for Playboy magazine in October 1999.
She appeared in two episodes of Freaks and Geeks in 2000. In 2004, she returned to the live stage (and to Laguna Beach, California, where she had attended high school), starring in the United States Premiere of Michael Weller's play What the Night is For, with Kip Gilman, directed by Richard Stein, at the Laguna Playhouse. She starred in the BBC comedy series, Broken News in 2005. She also plays Janine Foster, mother of Peri Brown, in the Doctor Who audio drama "The Reaping", produced by Big Finish Productions released in the United Kingdom in September 2006.
She also appeared in the 2002 She Spies episode, "Spy vs Spy".
She voices Anne Manx in the full cast recordings for the Radio Repertory Company of America. The science fiction series is currently shown as in pre-production for "Anne Manx 6".
She also has a music career, having made three records Taboo, Claudia Squared and Once Upon a Time as well as collaborating with some of the other cast members of Babylon 5 on the album The Be Five.