The Warriors' all-time leading try-scorer was originally contracted until the end of the 2018 NRL season but asked the Warriors for an early release in order to join Salford and experience playing in Europe.
A fixture at Mt Smart Stadium for well over a decade, Vatuvei has been restricted to just one NRL appearance in 2017. He had to battle shoulder, rib, hamstring and knee injuries over the past three seasons, which left him weighing up his career options.
The 28-test Kiwis international lasted only 53 minutes in the round three clash against the Bulldogs and was sidelined for five weeks before making a return to action in the second tier Intrust Super Premiership.
"This wasn't an easy decision to make," Vatuvei said.
"I've absolutely loved my time here at the Warriors playing alongside my brothers.
"I will never forget this club and just want to say a massive thank you to the club and the fans for their support over the years."
Warriors managing director Jim Doyle said Vatuvei was a club legend.
"We didn't make this decision lightly but after years of fantastic service to the Warriors, he's decided the time is right to head overseas and we didn't want to stand in his way.
"We wish him all the best for his future."
After making his first-grade debut in 2004, Vatuvei, Warrior #115, went on to make 226 appearances for the club.
'The Beast' quickly became a potent attacking threat on the Warriors' left wing and in 2015 became the first player in NRL history to complete the feat of scoring 10 tries or more in 10 consecutive seasons.
Vatuvei also leaves New Zealand's shores as the Warriors' all-time leading try-scorer with 152 tries. Stacey Jones is second on the list with 77.
Warriors fans will get the opportunity to farewell Vatuvei in style at this Friday's game against the Penrith Panthers in Auckland where the giant winger will be honoured before he departs for the United Kingdom.
"While Manu won't play against the Panthers, our fans will understandably want a chance to give him a fitting send off," Doyle said.
"They'll get that opportunity this week and we are encouraging as many as possible to come on Friday to show Manu just how much he means to them."
