Williams is best known for winning the silver medal in the 200 metres at the 2001 World Championships. In 2001 he was named Jamaica Sportsman of the Year. Williams has competed in the Olympic Games three times, in 2000, 2004 and 2008, reaching the semi-finals of the 200m on all occasions. He was on the bronze medal-winning 4 x 400 metre relay team at the 2000 Olympics. He finished seventh in the 200m final at the 2007 World Championships.