Chambers was named in the British squad for the 2012 London Olympics after the selectors took into account his trials win and his times from the previous year. Given the abrupt turnaround in his fortunes, he said: "For me representing my country in an Olympics is a privilege that should never be taken for granted. To be given the opportunity to do so in my home town has been a dream that at times has seemed very distant and is now a reality." He returned to the British relay team at the 2012 European Athletics Championships after a six-year absence but a botched baton change saw the team disqualified. At the Olympics he won his 100 metres heat in a season's best of 10.02 seconds, with a legal 2.0 m/s following wind, in his first Olympic race in twelve years. He was drawn in the same semi-final as Usain Bolt but Chambers' run of 10.05 seconds for fourth meant he did not make the final. His Olympics came to an end in the 4×100 metres relay heats as the British team made an illegal baton exchange.