Lynn played for the Queensland under-19 side and made his first-class debut as a 19-year-old against South Australia at the Gabba in March 2010. A week later, against Western Australia, he scored 139 runs in the second innings and effectively saved Queensland from defeat. He represents the Brisbane Heat in the Big Bash League. In his first season, he made 109 at an average of 21.80, in his second he made 175 at 35.00, including 51 off 29 balls against the Perth Scorchers and in his third he scored 198 runs at 28.28 with his best innings again coming against the Scorchers; this time he made 81.
Lynn made his Twenty20 international debut against England in Hobart on 29 January 2014. He made 33 off 19 balls, including three sixes, but did not get to bat in his second game.
He was a part of the Deccan Chargers team during the 2011 and 2012 Indian Premier League (IPL) tournaments but only got to play one match for the team in IPL 2012. He was bought by the Sunrisers Hyderabad for the 2013 competition but did not get the chance to play in a single match. For the 2014, season he was signed by the Kolkata Knight Riders and in his first game he was the man of the match, scoring 45 off 31 balls and taking a catch to dismiss AB de Villiers and turn the game in the final over. In IPL 2015, he was retained by the Kolkata Knight Riders but he got injured and was ruled out of the tournament. Johan Botha came in as a replacement.