"As I said last week 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.
"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."
In a message for Warriors members and fans, Tomkins said: "I'm fully committed to this club until the end of this season.
"You've been outstanding welcoming me in with your support whether it has been in Australia or at Mount Smart Stadium. It has been immense. It means a lot to me and to all the lads in the team. When I do finish up I'll take back some big memories of my time here."
Tomkins has been sidelined since the third-round clash against the Parramatta Eels on March 21 after partially tearing the posterior cruciate ligament in his left knee. He is being targeted for a return in the eighth round (against Gold Coast on April 25) or the ninth round (against Cronulla on May 9).