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"When I considered whether my immediate playing future was here in New Zealand and Christchurch, I didn't need to look far for the answer," Whitelock said.
"My wife Hannah and I have recently welcomed a new addition to our family, I am still genuinely excited to be playing rugby for these teams and I feel like there is still plenty more to achieve."
"There is more than enough to motivate me to keep playing and performing for these teams, so I am thrilled and honoured to have re-signed with New Zealand Rugby, the BNZ Crusaders and Canterbury Rugby through to 2020."
Whitelock (28) has been tipped in some quarters as a possible replacement captain, once incumbent Kieran Read retires
He has played 84 tests for the All Blacks, since making his debut back in 2010 against Ireland in New Plymouth.
He made an immediate impact, scoring two tries in that match.
In 2011, he was selected in the All Blacks Rugby World Cup squad and started every game, bar the first pool match. At the 2015 Rugby World Cup, he played in every game.
He became the most capped lock in his 80th test against Argentina last year, overtaking Ian Jones, and is currently the 11th most-capped All Black.
Whitelock is a Super Rugby centurion, making his Super debut in 2010. The son of former Junior All Black Braeden Whitelock, he is one of four Whitelock brothers to have represented Canterbury and the Crusaders.
Cousin Ben Funnell is also a current member of both squads. The Whitelock brothers and Funnell all moved south from Palmerston North to attend university in Canterbury, and went on to play for the Canterbury provincial side.
Sam first appeared for Canterbury in 2008.
All Blacks head coach Steve Hansen said having Whitelock's services for the next few years was a major boost for the national side.
"On behalf of New Zealand Rugby, as well as all New Zealand rugby fans, I want to congratulate Sam and his wife Hannah on his decision," said Hansen. "He's a world-class lock and, together with Brodie Retallick, forms one of the best international locking partnerships in world rugby at present.
"Sam is also great contributor to our environment - he thinks a lot about the game, is a flexible thinker, leads very well within the group and has become a very, very important component in the All Blacks.
"Once again, it's great to have another one of our key men re-sign with New Zealand Rugby," Hansen added.
Retaining Whitelock's formidable skillset and leadership qualities for the immediate future would also be invaluable for the Crusaders, according to head coach Scott Robertson.
"Sam is an incredibly important member of this team and has been an inspiration as our captain this season. He leads through his actions and has huge mana amongst the team.
"The example he sets, both on and off the field. is exemplary, so we are stoked that we will continue to have his positive influence in our environment."
Whitelock joins All Blacks cice-captain Ben Smith in re-signing through to 2020, while Owen Franks, Israel Dagg, Brodie Retallick, Aaron Smith, Julian Savea, Dane Coles, Sonny Bill Williams, Joe Moody, Patrick Tuipulotu, Liam Squire and Liam Coltman have all inked deals through to 2019.