Laumape, 32, played 15 Tests for the All Blacks between 2017 and 2020 and played 85 times for the Hurricanes. He played a season with Stade Francais before completing three seasons with Kobelco Kobe Steelers.
A former Junior Kiwi, he played 30 games for the Warriors in the NRL.
Laumape is the 30th player in Moana Pasifika's squad for next season and said one of the reasons he has returned is to be part of the first Moana Pasifika team to win the competition.
"There has to be a lot of hard work and many things behind the scenes that we'll have to do, but why can't our culture and people do something great in this competition?
"That's pretty inspiring and definitely motivating."
Palmerston North born and raised, Laumape played for New Zealand Schools with Moana Pasifika's captain Ardie Savea. They were Hurricanes, All Blacks and Kobe Steelers teammates.
Laumape said he wanted to play with a purpose, and playing for Moana Pasifika would be the closest thing he would get to playing for Tonga and its culture, while another reason was to play in front of his family again.
"One of the most special things I saw [from Japan] was seeing our Pacific brothers doing well and doing it the Pacific way. That stood out to me.
"It doesn't have to be all seriousness. Seeing the Pacific people support the team and the boys did a great job inspiring the young generation. I want to add to that over the next couple of years.
"Going into that environment, knowing that you can be yourself and when going into the workspace, your culture, the way you've been brought up, all relate."
Moana Pasifika coach Tana Umaga said it was exciting to have Laumape, a player who has proven himself on the international stage, on board.
"From his experience in league, the All Blacks, as well as in France and Japan, he has an open and mature outlook on the game. He's a great person who has done well for himself and his family and he'll integrate smoothly into our team environment."
In other Super Rugby Pacific signings, All Blacks wing Caleb Clarke has renewed his Blues contract for two seasons while the Highlanders will have the services of loose forwards Te Kamaka Howden and Veveni Lasaqa for another two seasons.