At the 2009 World Championships, Williamson failed to live up to expectations and was eliminated in the quarter-finals of the competition, recording 10.23 seconds after suffering a cramp. However, success came in the form of a relay medal, as he led off a team including Tyrone Edgar, Marlon Devonish and Harry Aikines-Aryeetey, and won the bronze, his first international relay medal. After the championships he took third at the Rieti IAAF Grand Prix, but finished last by some distance at the 2009 IAAF World Athletics Final. Although, he had won his first national championship that year, he had peaked outside of the major competitions. He stated that he was not sure how he had managed his 10.05 seconds win, but announced that he would return to Jamaica for a winter training camp to try to improve his consistency for the following season.