The Blues frontrower has agreed to join the Toulouse club for the next European season.
The 30-year-old has played 46 tests for the All Blacks and has played for the Blues since 2009.
He will still play for the Blues in next year's Super Rugby competition and is eligible for selection to play against the touring British and Irish Lions next June.
If selected, he would join Toulouse after the Lions series and in time for the French season.
Faumuina, who collected his first international cap in 2012, said leaving his homeland had been a difficult decision but he is excited by the opportunity in Europe.
"I would just like to thank New Zealand Rugby, the Blues and Auckland Rugby, for everything they have done for me throughout my career," Faumuina said.
"I'm looking forward to my last season in New Zealand, making it a successful one with the Blues and hopefully getting the chance to play for the All Blacks."
Faumuina was a member of the New Zealand squad that retained the 2015 World Cup, during which he came on as a second-half replacement in the final against Australia at Twickenham.
Toulouse, the four-time European champions, are fourth in the French Top 14 table.