The decision will keep the hulking back-rower with the famous locks in Melbourne until the end of the 2018 season.
Proctor has started the season in career best form, having played all 10 matches, taking his career tally to 114 first grade games. He represented the Kiwis in this year's ANZAC Test having made his international debut in the same match two years ago.
The 25-year old joined the Club straight from school and made his NRL debut in Round 10 of the 2008 season. He enjoyed success in 2009 as part of the Club's NYC premiership team and was also a key member of the Storm's 2012 premiership winning team.
Proctor will become a 10 year Melbourne Storm player at the end of this deal.
Proctor said it was important for him to show loyalty to the Club that had been loyal to him.
"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," Proctor said.
"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."
Storm Football Director Frank Ponissi said the Club was thrilled see Kevin re-commit.
"We understand the big decision Kevin had to make and we are absolutely thrilled he and his partner Leesa will be calling Melbourne home for a further four years. They are both popular members of the Storm family," Ponissi said.
"Kevin has been at our Club since leaving school seven years ago and during this time he has developed into an important senior player and leader.
"As well as being an integral part of the team, Kevin is extremely popular with his teammates, staff and supporters.Like