She started in the industry in 1993 working for DC Comics, with her first published work being as colorist on the "A True Son of Kahless" story in their Star Trek TNG Special 1, her only Star Trek-related work. Since then, Mulvihill has gone on to work on Wonder Woman (1993-2003), Nightwing, and 100 Bullets (since 2000). Other titles include Batman, Detective Comics, Greek Street, and Adventures in the Rifle Brigade. In 2004, she won the Will Eisner Award as Best Colorist for her work on Batman, Wonder Woman, and 100 Bullets.