"LOU Rugby is happy to announce the signing of Charlie Ngatai... who signed a two-year contract as of next season," the Top-14 team said in a statement on Tuesday.
The 27-year-old, whose only test for the All Blacks came in 2015, appeared set for a long stay in the team after the last World Cup in England but suffered a concussion in early 2016 that kept him out of rugby for more than 12 months.
"I'm likely looking to head overseas, and more likely over to France, at the end of the season," Ngatai told reporters in Hamilton earlier on Tuesday.
The Waikato Chiefs centre said his decision was influenced by the impact the concussion had on his career. He said he wanted to secure his financial future now rather than try to push his way back into All Blacks contention ahead of the 2019 Rugby World Cup in Japan.
"That's another reason why we looked overseas as well, you never know when your career's going to finish," he said, adding that the depth of talent in the All Blacks midfield would make it a challenge to break through.
"I guess a lot of it comes down to money. And then opportunity - there's a lot of young players coming through in New Zealand, and places in the All Blacks team are a lot harder."
Ngatai joins 16-test flyhalf Lima Sopoaga and the uncapped Wellington Hurricanes flanker Brad Shields as promising players heading abroad at the end of the 2018 Super Rugby season.
Shields, who has already said he is moving to English club Wasps, has been on the fringe of the All Blacks for a number of seasons without being selected and qualifies automatically for England through his parents.
Utility back Charles Piutau also left for Europe in arguably his prime in 2015, while loose forward Steven Luatua joined Bristol last year.
Both were in their mid-20s when they left and had been considered having important roles to play for the All Blacks in coach Steve Hansen's planning for the 2019 tournament, where the team are seeking a third successive title.
(Reporting by Julien Pretot and Greg Stutchbury in Wellington; Editing by Peter Rutherford and Christian Radnedge)
