Proctor, 25, has been with the Storm since he left school, and has made 114 first grade appearances.
He played for the Kiwis in this year’s ANZAC Test, having made his international debut in the same match two years ago.
He said: “I’ve invested a lot of time into the Club and agreeing to terms is about me showing my appreciation to Melbourne Storm and repaying the loyalty they have shown me in the seven years I have been here.
“My heart is with Melbourne, this is home for me and it would’ve felt weird to picture myself leaving the Club.
“In weighing up the decision, I just knew I would be happier here and you can’t put a price on happiness.”