Van Tornhout, 26, becomes the fourth winter signing for Killie, who previously added defender Ben Gordon from Chelsea, defender Michael Nelson from Scunthorpe and midfielder Dean Shiels, the son of manager Kenny Shiels, from Doncaster Rovers.
"[Van Tornhout] is over six feet tall, he holds the ball well and will connect the top end of the pitch for us," Coach Shiels said. "He moves well with a decent understanding of the game. He's a big lad so he'll offer us a different style. We've become a little bit predictable at times so he'll give us variety in attack."