Fiji overcame the first half sin-binning of Eloni Vunakece to register their opening win in Group A of the World Cup.
Two second half tries gave winger Akuila Uate a hat-trick as the Fijians built from a 12-4 interval lead to lead 32-4 with three minutes remaining.
The Irish scored late consolation tries through Damien Blanch and James Hasson but it was undoubtedly the Fijian day in front of a record Rugby League crowd at Spotland in Rochdale.
Tariq Sims had scored the Fijians first try of the second half and brother Korbin scored the Fijians other second half try, just beating Tariq to a high kick.
Fiji go top of the Group A table with once again the 2013 Rugby League World Cup providing an entertaining match in front of 8,872 spectators.