Jay Karnes was born in Omaha, NE and attended the University of Kansas, where he studied theatre, history, and political science. He has performed extensively in the regional theater, including in The Tempest, Two Noble Kinsman, Richard II, Macbeth, Coriolanus, Love's Labor's Lost, and Tom Stoppard's Arcadia, as a company member at The Oregon Shakespeare Festival; Dealing with Claire, The Birthday Party, The Seagull, Dangerous Corner, and The Tavern, with the Matrix Theater Company in Los Angeles; Richard III, A Midsummer Night's Dream, Jekyll, and The Tempest, at the Missouri Repertory Theatre; Neil LaBute's Filthy Talk for Troubled Times, directed by the author at the Westside dance project in New York; as well as roles at the Milwaukee Repertory Theater, South Coast Repertory Theater, Nebraska Shakespeare Festival, and the California Shakespeare Festival, among others.

In the late 1990s, Jay began working in television and film, and is perhaps best known for his portrayal of detective Holland "Dutch" Wagenbach in the Golden Globe winning drama "The Shield."

Jay is married to actress Julia Campbell and the couple have twins, a boy and a girl.