Kelly graduated from the Minneapolis College of Art and Design in 1998 where he studied under comic book artist Peter Gross. He worked with Peter Gross on the DC/Vertigo comic books Lucifer and The Books of Magic. He is now on the MCAD staff, teaching the occasional inking class, as well as classes for younger students. He has also moved on to work on other books, including guest inking responsibilities on American Virgin and penciling duties for AiT/PlanetLar's Giant Robot Warriors with Stuart Moore.
In addition to his comics art work he has had various Minneapolis area exhibitions of his painted work. He has produced illustrations for Time Magazine and Rolling Stone, among others.
He illustrated the entire twelve issue run of the Oni Press comics series Local, written by Brian Wood and a story arc ("The Cross + the Hammer") for Wood's Northlanders, Currently he is illustrating the DC/Vertigo ongoing series Saucer Country by Paul Cornell (March 2010)