Gregson Wagner's first film role was as Lisa in film Fathers & Sons, with Jeff Goldblum and Famke Janssen in 1992. She then had a small role in the movie Buffy the Vampire Slayer. Following that film she starred in several TV movies including Modern Vampires, Hefner: Unauthorized, and The Shaggy Dog. In 1995 she starred with her stepfather Robert Wagner in a Hart to Hart TV movie. She starred in the Wes Craven film The Outpost. In 1996 she co-starred with Jon Lovitz in the comedy High School High. In the 1997 film Two Girls and a Guy she played Lou, a sexually liberated young woman, who discovers that her actor boyfriend Blake Allen (Robert Downey Jr.) is cheating on her with Carla Bennett (Heather Graham). Gregson Wagner had a small role in the 1998 thriller Urban Legends in which her character Michelle is killed off in the first few minutes by a serial killer hiding in the backseat of her car. That same year she guest starred in an episode of Ally McBeal. In 1999 she played a heroin junkie in the Another Day in Paradise where she had an explicit sex scene with Vincent Kartheiser.