Born in Palmerston North and raised on a dairy farm in the suburb of Linton, 11 km south-west of the city, Luke was born into a rugby household with his grandfather being 1950's All Black, Nelson Dalzell, father Braeden being a former Manawatu and New Zealand Colts representative and 3 older brothers; George, Adam and Sam all going on to play for Canterbury and the Crusaders with George and Sam also becoming All Blacks.
2013 saw Whitelock win his 3rd ITM Cup in 3 years as Canterbury finished 2nd behind Wellington on the Premiership log, but were able to overcome the Lions 29–13 in the final.
Ahead of the 2015 ITM Cup, Whitelock was named as Canterbury captain, following in the footsteps of older brother, George, who led the Cantabrians to five successive national titles between 2009 and 2013.
Luke's captaincy got off to the perfect start as Canterbury went through the regular season with a record of 9 wins and 1 loss and after defeating Taranaki and Auckland in the playoffs they were crowned ITM Cup champions once again.
In 2013, Whitelock played in all 18 of the Crusaders matches as they were once again eliminated at the semi-final stage by the Chiefs who went on to defend their title by defeating the Brumbies in the final.
2015 would prove to be his final year with the Crusaders and it would also be his least productive with the franchise, starting just twice out of a total of 8 appearances as the men from Christchurch endured a disappointing campaign and finished in 7th place, just missing out on the playoffs.
Whitelock made his debut in the green and white jersey during the 2019–20 European Rugby Challenge Cup at Stade du Hameau, helping secure a win against Cardiff Blues.
Whitelock led the team to a crucial victory over Aviron Bayonnais at a packed Anoeta Stadium, a key match for securing their Top 14 status.
[13] In March 2024, he signed a two-year contract extension,[14] expressing his satisfaction with the club's direction and his family's enjoyment of life in Béarn, which has become their "second home.
[16][17][18] Whitelock earned his first call up to the senior New Zealand side ahead of the 2013 end-of-year rugby union internationals and debuted as a second-half replacement for Dominic Bird in a 54–6 victory over Japan in Tokyo.
[26][27] Savea performed outstandingly in Whitelock's absence, winning Man of the Match, as the All Blacks won the Rugby Championship for the third year in a row.
Ardie Savea's outstanding performance at number 8 against Argentina, as well as the arrival of then-uncapped Blues flanker, Dalton Papalii and the return of Matt Todd from Japan, as well as Liam Squire from injury, were seen as reasons for Whitelock's omission from the main 31-man group travelling to Europe for tests against England, Ireland and Italy.