Kilner was born in Baltimore, Maryland, the son of Dorothea, a kindergarten teacher, and Edward Kilner, who worked in advertising sales and insurance. He made his first television appearance on an episode of The Cosby Show in 1989. He is perhaps best known for playing the main protagonist in the first season of Earth: Final Conflict, and Officer Dean in The Stoned Age. In 1995-96, Kilner starred in Almost Perfect as the romantic interest of Nancy Travis, who played a screenwriter, but Kilner was written out of the show in the second season premiere. In 2009, he appeared on a few episodes of the Joss Whedon show Dollhouse.