Turner was born in Colorado Springs, Colorado. His father, George Turner, was in the Air Force and moved his family around often during Jim's youth to several locations, including Quebec, Arizona, and Iowa. Turner married Lynn Freer in 1992 and they have a son, Otto. He is a longtime member of the comedy troupe Duck's Breath Mystery Theatre. He co-starred for seven seasons in HBO's comedy series Arliss as Kirby Carlisle, an ex-football-star-turned-agent and an old buddy of sports agent Arliss Michaels (Robert Wuhl). Turner has appeared in 22 feature films and shorts, 28 TV series and appearances, 18 stage plays, one-man-shows, and comedy tours. He has created characters ranging from pinheads to Pinocchio. He has worked with Joel Schumacher, Robert Wuhl, Jack Black, Paul Bartel, and Tracey Ullman. From 1987 to 1990, Turner performed on MTV and Ha! as Randee of the Redwoods, a character he adapted from his days with Duck's Breath Mystery Theatre. As part of a marketing stunt, Randee became the dark horse candidate for President. Turner studied at the University of Iowa. Turner is a founding member of the Los Angeles-based comedy group 2 Headed Dog with comedians Mark Fite, Dave (Gruber) Allen, and Craig Anton.