The Brit entered the season finale knowing that he'd claim the Drivers' Championship if he finished inside the top three.
He quickly fell behind his two title rivals and was under pressure from Charles Leclerc throughout the race, but he kept his cool to get the job done.
With McLaren producing the strongest car, Norris entered the season as the title favourite in the eyes of many, but was very much second best to teammate Piastri in the first half of the campaign.
At the end of the Dutch Grand Prix in late August, the Brit trailed the Aussie by 34 points, partially because of reliability issues but mainly because of a lack of consistency; while he was faster than Piastri on his day, the other McLaren driver was making far fewer errors and was always there to take advantage when Norris did.
However, with nine rounds to go, Norris began to hunt his teammate down. The tables turned, with him largely flawless and errors creeping into Piastri's weekends, and that saw the former beat the latter in six consecutive races and take the lead of the championship in Mexico.
He looked set to claim his first title with three race weekends left, but he had a second-placed finish in Las Vegas taken from him when both he and Piastri were disqualified due to a technical infringement from McLaren. With Verstappen victorious, the Dutchman was now back in contention.
McLaren then made a strategic mishap in Qatar, allowing the reigning champion to pass both of their drivers and win to head into the season finale in Abu Dhabi ahead of Piastri and just 12 points behind Norris.
The Dutchman claimed pole position at the final race, but Norris qualified in second and steadied the ship after being passed by Piastri at the start to finish third and seal the title by two points.
Norris becomes the first McLaren man to win the Drivers' Championship since Lewis Hamilton back in 2008, and the eighth in their history, joining an illustrious list also containing Emerson Fittipaldi, James Hunt, Niki Lauda, Alain Prost, Ayrton Senna and Mika Hakkinen.
He's the 11th British driver to win the title and the first not named Hamilton since Jenson Button in 2009.
It won't be easy with Piastri likely to only get better and McLaren set to be less dominant from next season, but being aged just 26, he now has plenty of time to add more titles to his name.