Anthony Gelling's Warriors contract will last just one season after he signed a Super League deal with Widnes from 2019.
Gelling has penned a two-year contract, taking him back to England where he enjoyed six productive seasons with Wigan.
The 27-year-old centre has struggled to break into the Warriors' first-choice starting line-up, making six appearances.
He made his third start in last week's loss to Cronulla, when he scored his second try for the club.
The Auckland-born Cook Islands international was a prime target for Widnes according to their interim head coach Francis Cummins.
"He has ability to produce something out of nothing," Cummins told the club's website.
"Players of his quality are few and far between, and we are excited that he will be representing our club."
Widnes, who sacked head coach Denis Betts in May, are bottom of the Super League, having won lost 16 of their 19 league games this season.