Fumusa began his acting career in the Chicago theatre scene, before moving to New York and making his Broadway debut in 1998 in a revival of Wait Until Dark opposite Marisa Tomei and Quentin Tarantino. He has originated roles on the Broadway stage in such plays as the Tony Award-winning Take Me Out, Tape, and [sic]. He has previously had a recurring role in As the World Turns, and guest starred as Carrie Bradshaw's highly critical ex-boyfriend Jim in the episode of the HBO series Sex and the City, titled "Frenemies." He starred in the 2016 film, 13 Hours: The Secret Soldiers of Benghazi, directed by Michael Bay.