He won his fifth national title in the 60 m in 2012 with a season's best of 6.58 m. A third consecutive podium finish came at the 2012 IAAF World Indoor Championships, where he pipped Trell Kimmons to the bronze medal. Chambers was given the chance to return to the Olympic stage after the Court of Arbitration for Sport (CAS) decided in favour of the World Anti-Doping Agency over the validity of British Olympic Association's (BOA) Olympic ban by-law. CAS agreed that the law was non-compliant with the World Anti-Doping Code, to which the BOA was signatory due to its connection with the International Olympic Committee. Chambers ran a 150 m-straight best of 15.27 seconds at the Great City Games in May then won the 100 m Olympic trial race, holding off emerging teenager Adam Gemili. His absence from the major track circuit came to an end with a run at the Diamond League London Grand Prix, although he did not achieve the Olympic "A" standard time there.