Morris's first role was a minor one in the 1991 tele-movie Long Road Home. Several other small parts followed, including a bit part as a psychiatric patient in the Oscar-winning As Good as It Gets. Her breakthrough role came as Lt. Annalisa "Stinger" Lindstrom in the television series Pensacola: Wings of Gold in 1997 for two seasons. Morris continued to work in films (notably ones directed by Rod Lurie) and had a brief stint on the Xena series in 1999 as Najara.
After seeing her in the film, The Contender (which DreamWorks distributed), Steven Spielberg cast her in two successive films. Her scenes as a rock star in A.I.: Artificial Intelligence, which required Morris to take intensive singing and guitar lessons were cut by the director, which was particularly agonizing for her. In Minority Report, she portrayed the tormented wife of Tom Cruise's character.