The 26-year old, a Grand Final winner with Saints, will join up with the Black & Whites for the 2020 campaign, bringing to end an eight-year spell with the Merseyside club.
He was part of the St Helens squad that won the Super League Grand Final in 2014, as well as being part of the squad that won the League Leaders Shield last season.
He has maintained an impressive try-scoring record throughout his career, crossing for 99 tries in 141 career appearances, including 86 tries for St Helens.
Swift made his Super League debut in 2012 and he has nine career hat-tricks to his name, including in his league debut against Widnes.
True to his surname, Swift is known for his electrifying pace and he is regarded as one of the fastest wingers in the competition.
Previous Clubs: St Helens, Whitehaven (loan), Rochdale (loan), Sheffield (loan), Leigh (loan)
Community Club: Blackbrook
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