Haddin's family moved to Queanbeyan in 1989 when he was 12 and he played for the Queanbeyan District Cricket Club Juniors to the age of 15 before joining the Australian National University Grade Cricket Club, representing 1st grade at age 16. Haddin was selected in the first ever Mercantile Mutual Cup season of 1997–98 for the ACT Comets, with whom he began his professional cricketing career. In the 1999–2000 season, he began playing for the New South Wales Blues to pursue further cricketing opportunities. Since then, he has produced several memorable batting innings, including a top score of 133 against Victoria. Haddin was signed by Chennai Super Kings in the 2010 IPL. In the 2011 Indian Premier League season, Haddin was contracted by Kolkata Knight Riders for US$325,000.