Cowley's debut at an international athletics competition was at the 2008 World Race Walking Cup where he competed in the junior 10kilometre race; finishing 39th in at time 45minutes and 24seconds. He then competed at the 2010 World Junior Championships in Athletics where he finished 17th in the 10kilometres event. Cowley competed in two more World Race Walking Cups in 2010 and 2012. At the 2010 competition he once again competed in the junior 10kilometre race. This time he finished 15th. At the 2012 edition of the IAAF World Race Walking Cup he competed in the senior 20kilometre walk and finished 90th. He competed in his first World Championships in the 2013 competition where he finished 50th out of 64 athletes in the 20kilometre walk. The 2014 World Race Walking Cup was Cowley's fourth World Race Walking Cup. He finished 57th in the senior 20kilometre walk. Cowley competed in the 2015 Summer Universiade, his first Summer Universiade. His finish of 13th in the 20 kilometres walk was his best ever finish at an international competition. Cowley's best finish at a World Race Walking Cup came in the 2016 edition when he finished 39th in the senior 20kilometre walk. Cowley qualified for his first Summer Olympics in 2016. At the 2016 Summer Olympics he will compete in the 20kilometre walk.