Haggerty's usual position is prop-forward. He is a specialist impact player, coming off the interchange bench. He is the son of former St Helens forward Roy Haggerty.
He was a member of the Ireland squad for the 2008 Rugby League World Cup. Although relatively unknown in Australia prior to the tournament, his performances from the bench in the World Cup earned widespread praise from both fans and pundits, with many Australians going as far as to chant 'sign him up' during games.