One of the first things I learned about acting was, the only person you compete against is yourself.

Harris who sang with the Fred Waring chorus and worked at the bookstore of the Art Institute of Chicago. Two years later his family moved to New Mexico and he followed after having discovered his interest in acting in various theater plays. He appeared as a vengeful mobster in David Cronenberg's A History of Violence (2005) and as a police officer alongside Casey Affleck and Morgan Freeman in Gone Baby Gone (2007) directed by Ben Affleck.

He is best known for his performances in Pollock Appaloosa The Rock The Abyss A Beautiful Mind A History of Violence Enemy at the Gates The Right Stuff Gone Baby Gone Paris Trout Jackknife Empire Falls and Game Change. Harris has also narrated commercials for Home Depot and other companies.