Prior to working on Key & Peele, Dunn was a Writer and performer on madTV, from 2005 to 2009. He has also appeared in Parks and Recreation, Nick Swardson's Pretend Time, Game Shop, Burning Love,a small part on College Humor's "If Google Was a Guy" and currently co-stars in Superstore on NBC. Dunn hosted the comedy variety show RT-ES, produced by Rooster Teeth Productions, and co-starred in their sci-fi action comedy Lazer Team in 2016.