Following his world junior win, he set the current NAIA record as a member of the UBC Thunderbirds and was the bronze medalist at the 2006 NACAC U-23 Championships. He jumped a personal best of 2.27 m to win the Canadian title in 2007 Canadian Senior Championships. He is a member of the Valley Royals Track and Field Club and is coached by Ziggy Szelagowicz.
In 2008 Mason improved his personal best during the indoor season, to 2.30 in January in Seattle. At the 2008 World Indoor Championships he finished eighth. He made his Olympic debut a few months later at the 2008 Beijing Olympics and placed eighth in his qualifying group with a jump of 2.25 m, although he missed the final.[2] Competing as a student-athlete, he took the silver medal in the high jump at the 2009 Summer Universiade.[3] The year after he represented Canada at the 2010 Commonwealth Games with a seventh-place finish in the final.[4]
He cleared 2.31 m for the first time at the Baie-Mahault Grand Prix in Guadeloupe, winning the event with a meet record mark.[5] In 2015 Mason improved his indoor personal best to 2.31m at the Millrose Games and his outdoor best to 2.33m at the Edmonton Track Classic.[citation needed]