After making his Queensland Reds debut in 2011, Harris was selected to fill the void of flyhalf after fellow Queensland Reds played Quade Cooper had succumbed to injury during the 2011 Rugby World Cup. Harris immediately made an impact as he broke the Super Rugby record for most consecutive goals (penalties, conversions etc.) with 24. He also broke John Eales' Queensland and Australian record for most goals in a game with 9 (7 penalties, 2 conversions). He became a viable kicking option for the Reds but suffered injury a few weeks later. In June 2012 he was selected to play his first test match against Scotland. In May 2014 it was announced that Harris would be joining the Melbourne Rebels for the 2015 and 2016 seasons.
Harris was qualified to represent the Wallabies through his Australian-born grandmother, and was selected at inside centre for the test match on 5 June 2012 against Scotland. He scored 6 points in this game, the only points for Australia in a 9-6 loss to Scotland. Two weeks later he was on the bench in the second test against Wales in Melbourne on 16 June 2012, coming on for an injured Berrick Barnes. He scored the winning goal for the match to secure a 25-23 win for the Wallabies.
After missing selection for the Wallabies at the 2015 World Cup, Harris was named in the 39-man squad for the 2016 international series against England.