Kasey Mahaffy was born and raised in Portland, Oregon, long before its pour-over coffee and airport carpet fame. He received a BFA in acting from Southern Oregon University.

Theatre credits include Peter and the Starcatcher, Crimes of the Heart, You Nero, An Italian Straw Hat, and Taking Steps (South Coast Repertory); The Best Brothers and The Violet Hour (Ensemble Theatre); The Tempest (A Noise Within); the world premiere of Partners (Actors Theatre of Louisville); Clybourne Park and Metamorphoses (Pioneer Theatre); You, Nero (Arena Stage/Berkeley Repertory); The Miracle Worker and Assassins (Berkshire Theatre); The Merchant of Venice (Portland Center Stage); and Tartuffe and Much Ado About Nothing (Sonnet Repertory).

Television credits include Rick Joy on HBO’s Getting On and Dom on ABC's Modern Family, as well as American Horror Story: Asylum, Castle, Franklin & Bash, Bad Teacher, CSI, Bones, Law & Order: LA, and ER, among others.