Greig’s competitive career began in 2008 when he competed in the World Junior Championships Skating in Italy. From there, he steadily improved, making his debut on the senior international stage at the 2012 World Championships in Heerenveen, Netherlands. In 2014, Greig reached the pinnacle of his career when he competed in the Winter Olympics in Sochi, Russia. He represented Australia in both the 500m and 1000m events. Following his Olympic appearance, Greig continued to compete, competing in numerous World Cup events and World Championships. He also became a multiple-time national champion in both the 500m and 1000m events.