The re-signing of the two-time World Cup champion will see Whitelock anchor a core group of All Blacks who have signed with NZR post-2019.
New Zealand Rugby CEO Steve Tew said: “This is a major re-signing for us and we’re absolutely delighted that Sam has chosen to sign a four-year deal. He’s a world-class player, an All Blacks centurion, the most capped All Blacks lock of all time and he carries immensity.
“His recommitment alongside a number of other key players gives us a strong foundation for the next four years. I know the news will be welcomed by fans here in New Zealand and around the world.
“As well as Sam, I’d like to thank his wife Hannah and his agent Warren Alcock who played a key role in the contract negotiations and were fantastic to deal with.”
Under the terms of the deal, Whitelock will take a break from New Zealand rugby at the end of this year to take up a short-term contract with Japanese Top League side Panasonic. He will miss the 2020 Super Rugby season and return to New Zealand at the end of the Japanese club season in May 2020.
Tew said: “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.
“He’ll have a short break away with his young family and experience a different culture, before returning to New Zealand. We think having a short playing stint in Japan as part of a long-term, four-year commitment is a win-win for him and us.”