He won a grand final with the Storm in 2012, made his New Zealand debut in the same season, and has since gone onto play another 12 matches for the Kiwis.
He averaged 32 tackles per game this year as he helped the Storm to another grand final, producing 18 offloads and 27 tackle busts.
"It has been a long process and I needed to feel comfortable with the decision," Proctor said. "I have had a successful time at the Melbourne Storm and made some great friends, but now I am looking forward to joining Neil and the Titans' players and contributing to the team's success."
Despite being born in New Zealand, Proctor and his partner, Leesa, grew up on the Gold Coast, prompting the move.
"This is a great opportunity to return home to the Gold Coast with my young family to be closer to all of our family," Proctor said.
Proctor's signing comes three weeks after former co-captain and lock Greg Bird was released by the club to head to the Catalans Dragons in the English Super League.
They have also previously added Brisbane prop Jarrod Wallace to their forward pack, after losing Luke Douglas to St Helens in England.
-AAP