Fifita was chosen in the 24-man Australian squad for the 2013 Rugby League World Cup. On 26 October, he made his international debut for Australia against England where he played off the interchange bench in the 28–20 win at Millennium Stadium. In his third match for Australia, against Ireland, Fifita scored his first international try in the Kangaroos 50–0 win at Thomond Park. In the Kangaroos semi-final match against Fiji, Fifita scored the last try of the match in the 64–0 win. It was the last try ever described by BBC rugby league commentator Ray French. During the tournament, Fifita played in 6 matches and scored 2 tries for Australia, including playing off the interchange bench in the Kangaroos 34-2 World Cup win over New Zealand at Old Trafford.