Djokovic destroys Sinner to win record seventh ATP Finals title
The Serb lost to home favourite Sinner earlier in the week in the group stage, but exacted revenge with a sublime display to claim a 6-3 6-3 victory.
A sell-out crowd in Turin's Pala Alpitour had hoped to cheer Sinner (22) to the biggest title of his career but Djokovic was simply in a different league.
The world number one dropped only two points on serve in the opening set and once he had broken Sinner's serve in the fourth game it was largely one-way traffic.
At one point Djokovic won 14 points in a row against a player ranked fourth in the world before Sinner briefly slowed the march of the 24-time Grand Slam champion.
Sinner avoided going a double break of serve down as Djokovic surprisingly failed to make a passing shot and Sinner then had points to break back in the sixth game but could not convert either of them.
Djokovic also failed to convert break points that would have given him a 5-2 lead as a few errors crept into his game.
The crowd tried their best to energise their man but Djokovic moved on towards victory and a Sinner double fault ended the contest. Djokovic moves past Roger Federer to stand alone as the most successful player in the tournament's history.
His win concludes a year in which he won three of the four Grand Slam titles and seized back the world number one spot from Carlos Alcaraz and worryingly for the chasing pack he will head into 2024 looking as dominant as ever.
"This is very special," Djokovic, who was joined by his children Stefan and Tara, said on court.
"One of the best seasons I've had and to crown it against Jannik who has been playing so well is phenomenal.
"The way Carlos (Alcaraz) and Jannik have been playing I had to step it up."
Djokovic also outclassed Spain's Alcaraz in Saturday's semi-finals although his place in the last four had been in doubt after his narrow loss to Sinner in one of the matches of the year. Ironically it was Sinner's subsequent defeat of Holger Rune that kept Djokovic alive at the year-ender.