After competing in the IAAF World Junior Championships in 2002, Hession made his major championship debut for Ireland the same year, at the 2002 European Championships where he finished 7th in his heat in a time of 21.28. The following year Hession missed the World Championships but was rewarded with silver medal in the 200 m at the World University Games. Two years later Hession won bronze in the 2005 edition. He followed this up with a disappointing run in his first World Athletics Championship. In the 2006 European Championships Hession ran poorly in the semi final and with a time of 20.80 was eliminated.