Crusaders lock Whitelock added four years to his contract, committing himself through to the 2023 World Cup in France.
The 30-year-old is regarded as the man most likely to take over as New Zealand skipper when incumbent Kieran Read stands aside after this year’s World Cup in Japan.
He has led the All Blacks five times in Tests, all resulting in wins.
One of the world’s premier forwards, Whitelock can expect to be a central figure in All Blacks teams through the next World Cup cycle and should strongly challenge the world record for Test longevity if he remains injury free.
Having played 108 Tests since his debut as a 21-year-old in 2010, five more seasons in the top flight would push him well past 150 caps. The current world record-holder with 148 Tests is former All Blacks captain Richie McCaw.
A clause in Whitelock’s contract will allow him to take up a short-term contract with Japanese club Panasonic, beginning at the end of this year.
NZR chief executive Steve Tew said Whitelock would be given dispensation to bypass selection regulations and be eligible immediately for the All Blacks upon return.
“We know our players have a number of choices to make when it comes to where they play their rugby and we have to be flexible when it comes to renegotiating with our leading players, and that’s what we have done with Sam,” Tew said.
He described Whitelock’s retention as crucial in the fight to keep top Kiwi players at home.
Among those still to commit beyond this year are influential five-eighth Beauden Barrett and lock Brodie Retallick, who has formed a world-class second-row partnership with Whitelock in recent seasons.
Whitelock was grateful to have the chance to step away from the intensity of New Zealand Rugby for six months.
“Ultimately, this decision allows me to take some time with my family to experience a new rugby environment in Japan, before coming back refreshed and ready for the remainder of 2020 and beyond,” he said.
All Blacks coach Steve Hansen hailed Whitelock’s retention.
“He has been a hugely respected leader in our group for some time now,” he said.
“He’s a deep thinker on the game, cares passionately about the All Blacks and has done incredibly well in the handful of Tests which he has captained so far.”