In 1994, Robertson was cast in the series regular role of Clare Arnold in the Fox teen drama "Beverly Hills, 90210". She starred in the show from 1994 to 1997, during seasons four to seven. In 1997, her ex-boyfriend, director Gregg Araki cast her as Lucifer, one of a group of bored, alienated, and very horny Los Angeles teens in the black comedy drama film "Nowhere". She later had a role in his other film, called "Splendor" (1999). Robertson also has appeared in several films during her career. She appeared opposite Luke Wilson in romantic comedy "Dog Park" (1998), in Sally Field's directed comedy-drama "Beautiful" (2000), and the parody movie "Scary Movie 2" (2001). She later had more serious roles with the 2002 independent drama film "XX/XY", opposite Mark Ruffalo. In the same year, Robertson played the role of Evelyn Dick, a Canadian convicted murderer, whose trial remains the most sensationalized event in Canadian criminal history, in the made-for-television movie, "". Robertson was nominated for a Gemini Award for her performance in the film.