McCullum spent the last three years at Western Michigan and led the Broncos to a 20-11 record and a National Invitation Tournament berth this season.
"I'm most appreciative of the opportunity WMU provided me to reach my lifetime goal of becoming a head coach at the NCAA Division I level," McCullum said. "I'm extremely proud of the progress made over the last three years and of the direction the program is headed."
McCullum will replace Seth Greenberg, who left South Florida to take over at Virginia Tech. The Bulls finished 15-14 last season
In seven seasons at South Florida, Greenberg's teams posted a 108-100 record. He twice took the Bulls to the NIT but failed to make the NCAA Tournament.