The 26-year-old has been granted an early release from the final year of his Warriors contract on compassionate grounds, with Tomkins citing homesickness for his decision to leave.
Wigan have agreed to repay $389,000 of the world record $1.34 million transfer fee the Warriors paid for Tomkins back in 2013.
His exit is conditional on 2016 fullback signing Roger Tuivasa-Sheck's move across to the Warriors from the Sydney Roosters, with the Kiwis test flyer's contract set to be registered by the NRL after round 13.
"I'm pleased about having the opportunity to go back earlier than planned and to have the chance of playing alongside my brothers Joel and Logan with Wigan next year," Tomkins said.
"I hadn't expected things to play out like this but there are lots of things I have been missing about home, most of all family and friends."
Tomkins is recovering from a knee injury but is in line to make a playing return in round eight (against Gold Coast on April 25) or nine (against Cronulla on May 9).
- By David Skipwith of the New Zealand Herald
