An alumnus of the University of Illinois and the Lindemann Young Artists Program at the Metropolitan Opera, Gunn has had a steadily rising career even since his 1997 appearance as Oreste in Gluck's Iphig_nie en Tauride at Glimmerglass Opera (and subsequently at New York City Opera). Among his important roles recently have been Guglielmo in Mozart's CosÐ fan tutte, Zurga in Bizet's The Pearl Fishers, Papageno in Mozart's Die Zauberfl‹te (notably in the English-language version of Julie Taymor's staging for the Metropolitan Opera), and especially the title role in Britten's Billy Budd, which he has played at major companies in North America and Europe. He played the male lead, Clyde Griffiths, in the 2005 world premiere production of Tobias Picker's An American Tragedy at the Met.

Gunn has also performed widely in concert, both with major U.S. and European orchestras and in recital with his pianist wife, Julie Jordan Gunn. He won the Metropolitan Opera National Council Auditions, a 1997 Tucker Foundation Career Grant, the 1998 ARIA Award and the inaugural Beverly Sills Award in 2006.

Gunn's first disc for Sony BMG, to be released this August, is titled Just Before Sunrise; it includes songs by, among others, Gene Scheer (the librettist of An American Tragedy), Ben Moore, John Bucchino, Jimmy Van Heusen, Tom Waits, Billy Joel and Sting. Among his collaborators on some tracks are the 20-year-old jazz piano prodigy Eldar and Broadway star Kristin Chenoweth.