Green, 25, had two-years left on his deal at Craven Park, but has been signed by the Warriors to replace Dream Team selection Brett Finch, who will return Down Under at the end of the year.
Head Coach Shaun Wane said: “I am really excited to have Blake Green joining us. We have admired his style of play for some time at Wigan with his ability to attack the line, his kicking game and his strong defence. He will be a great addition to our squad and has all the qualities we need both as a player and a person.”
He said: “I’m really excited to be given the opportunity to play for the Wigan Warriors. They are a great club with a proud history which I’m sure will only improve my game. I’d like to thank Neil Hudgell and Hull KR for the way they have treated me over the last two years and will leave them with only good memories and close friendships.
“I am looking forward to this new chapter in my playing career with Wigan and hope to play a key role over the next couple of seasons as the team look to build on recent successes.”