John Barnett started out playing rugby union with Newtown RUFC, appearing five times for Australia. He was named to the New South Wales provincial team in 1905. He was selected for the 1908-09 Wallaby tour of the British Isles and France. During that tour Barnett, a hooker/prop, competed at the 1908 Olympics, winning a gold medal. On returning to Australia Barnett turned professional and played rugby league, joining the Newtown Club in Sydney. He competed in two Ashes’ Tests against Great Britain in 1910 when they toured Australia, making him a dual-code rugby international. In 1913 he toured New Zealand with the NSW Blues. Barnett died very young from meningitis, at only 38-years-old.