Morris' first role was a minor one in the 1991 telemovie 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. She played it 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.

After seeing her in the film The Contender, which Dreamworks distributed, Steven Spielberg cast her in two successive films, but her scenes as a rock star in A.I.: Artificial Intelligence which required her to take singing and guitar lessons were cut by the director while his Minority Report was filming. In the latter, she portrayed the tormented wife of Tom Cruise's character.

In 2003, Morris won the lead role of detective Lilly Rush in the CBS dramatic series Cold Case in which she plays a passionately conce