On 30 July, Williams played his first home test match during the second game of the 2011 Tri Nations Series. On 9 September he played in the opening match of the 2011 Rugby World Cup. A week later he scored his first test rugby tries during New Zealand's second game, in which he played on the right wing. The match was also the first time he had played outside the centres since playing in a handful of games on the wing and in the back row for Toulon. He scored his third try of the tournament against France, in his second consecutive game playing on the wing. On 2 October, Williams scored in his third consecutive match, whilst playing against Canada. New Zealand went on to win the tournament, with Williams amassing a Rugby World Cup record of three tries as a substitute player.