NBA legend Russell Westbrook has officially announced his retirement from professional basketball after an extraordinary 18-season career in the league.

The 37-year-old former MVP confirmed the decision on Wednesday via an emotional video posted to his social media, narrated by Hollywood actor Michael B. Jordan.

'Sometimes you don't even know when you've already watched the end,' Westbrook wrote alongside the announcement. 'You had to be there. And now it's over.'

Selected fourth overall in the 2008 NBA Draft by the Seattle SuperSonics - just before the franchise relocated to become the Oklahoma City Thunder - Westbrook went on to become one of the most explosive and ruthless point guards in basketball history.

His defining individual campaign came during the 2016-17 season with Oklahoma City, where he made history by becoming the first player since Oscar Robertson in 1962 to average a triple-double for an entire season.

Westbrook racked up a record-breaking 42 triple-doubles that year, securing the NBA MVP award and etching his name forever in the league's record books.

Remarkably, the Long Beach native went on to average a triple-double across three more full seasons - twice more with the Thunder and once with the Washington Wizards - cementing his status as the NBA's all-time triple-double leader.  

Over the course of his 18-year journey, Westbrook accumulated an incredible collection of accolades, including nine All-Star selections, nine All-NBA team honors, two scoring titles and three assist titles. 

He was also named to the NBA's 75th Anniversary Team celebrating the greatest players in league history and earned a Gold Medal with Team USA at the 2012 London Olympics. 

After spending his first 11 seasons as the heart and soul of the Thunder franchise, Westbrook embarked on a well-traveled final stretch of his career that saw him embrace shifting roles across the league.

His journey included high-profile stops with the Houston Rockets, Wizards, Los Angeles Lakers, Los Angeles Clippers, Denver Nuggets, and Sacramento Kings.

Westbrook leaves the game as one of the most statistically dominant guards to ever step onto the hardwood.

He finishes his storied career ranked 14th on the NBA's all-time scoring list with 27,176 points, alongside fifth place in all-time assists (10,351) and 14th in steals (2,038).