 He started playing golf at the age of five, learning the game at the Witbos Golf Club in Noorderwijk, Belgium.In 2010, he attended the University of Illinois for which he won the individual 2011 Jack Nicklaus Invitational and the individual 2012 NCAA Division I Championship in his second year; the next year, he finished second with his team at the 2013 NCAA Division I Championship and won the individual 2013 Big Ten Conference Championship.In summer 2013, Pieters decided to forgo his senior year at the University of Illinois and turn professional.