Gasnier was named sole captain of the Dragons for the 2008 season. He paired up with Matt Cooper in the centres. Gasnier was selected to play for Australia on 9 May and scored the first two tries. He was selected for Origin I against the Maroons, and helped set up five tries. He was also picked for Origin II despite carrying an injury, but was unable to play the third game. In July, Gasnier reported that he would switch to rugby union at the end of the season to link up with French club Stade Français. Gasnier played his final game for the Dragons against the Manly Sea Eagles at Brookvale in the 3rd Qualifying Final, scoring the Dragons' only points.