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He will leave at the end of the 2017 season.
Kerr-Barlow has been the in-form halfback of the first three rounds of Super Rugby with impressive showings against rival number nines.
He made five appearances for the All Blacks last season including a starting spot in the side's test against Italy in Rome.
The 26-year-old said it was a tough decision to join the Top 14 leaders.
"It was an extremely hard decision to make, but I feel it is the right one for my family and myself. I've always wanted to play rugby in New Zealand and to represent teams like Waikato and the Chiefs which is where my family comes from. It was a childhood dream of mine to become an All Black and it has been a privilege to represent my country," he said.
"Over the past couple of months I've thought long and hard about going overseas. I had really good contact with the Chiefs and the All Blacks throughout the process, but ultimately the opportunity to play rugby with La Rochelle and experience the French culture with my family was the right decision for me. At this point in time, I'm 100% focused on helping the Chiefs to another Super Rugby title and making the best of every moment I have left to play rugby in New Zealand."
Melbourne-born Kerr-Barlow arrived in New Zealand in 2004 as a 13-year-old and attended Hamilton Boys High School. The hard-working halfback made his debut for Waikato in 2009 and in 2010 he was part of the New Zealand Under-20 side that won the Junior World Championship in Argentina.
Kerr-Barlow made his Super Rugby debut for the Chiefs in 2011 against the Brumbies.
Since then the clinical number nine has become a mainstay for the Chiefs, dotting down seven times in his 70 appearances to date.
In 2012 he made his All Blacks debut against Scotland and has played 25 tests for his country, 23 off the bench.
Chiefs head coach Dave Rennie said: "Tawera is one of the nicest guys you'll meet and has been a pleasure to work with. Caring and competitive are two traits that stand out, but it's his work ethic and leadership around defence that makes him world-class. Tawera is in the form of his life, we wish him well."