Paleaaesina will leave the Warriors at the end of the season, club CEO Mick Watson said.
Paleaaesina's manager Peter Brown secured the deal during a trip to England ahead of the NRL's June 30 anti-tampering deadline.
Watson said Paleaaesina had signed a lucrative contract with Wigan.
"We wanted to retain Iafeta and we did all we could to try to accommodate him," Watson said.
"But with the experience he has gained and the salary cap restraints in the NRL we couldn't compete with the offer he had from Wigan."
"No club in the NRL would be able to come close to it."Like