Max Verstappen took the chequered flag, but all eyes were on the young Italian who takes the crown at the age of 20 years and 68 days, more than three years younger than Sebastian Vettel in 2010.
He is the first Italian to win the title since Alberto Ascari in 1953.
“We did it. I wouldn’t be here without Mercedes, without my family,” said an emotional Antonelli who has won nine races so far this season.
“I am very grateful for this moment, it will be with me forever. I am speechless, just trying to process what happened.
“It’s been an incredible season and to share this podium with Max and Lewis (Hamilton) is incredible. I am looking forward to some more battles in the future.”
The race broke into two parts as it was suspended after 46 of the 71 laps following a crash involving Cadillac’s Valtteri Bottas.
The Finn’s suspension on the front left side had collapsed causing his wheel to buckle and making him a helpless passenger as his car flew backwards off the track and slammed into the barriers.
The 37-year-old Bottas was slow to emerge from his car but waved to the crowd as he walked away, with all the other cars returning to the pits to await a restart.
Antonelli, who needed just to finish in the top nine to seal the title, was running third in his Mercedes when the race was stopped behind Red Bull’s Verstappen and the Ferrari of Charles Leclerc.
His nearest challenger teammate George Russell was out of the running after suffering a poor start dropping from second on the grid to fifth and struggling with his power.
Russell had to win to have any hope of prolonging the title race.
Lewis Hamilton, who started on pole and also needed to win to push Antonelli, was furious with his Ferrari teammate after an incident at the start that saw Leclerc leave the track and steal the lead.
The Monegasque was handed a five-second penalty, but he retained track superiority over Hamilton.
That changed on the restart when Hamilton powered past Antonelli and Leclerc and bumped wheels with Verstappen before settling into second.
There was a further yellow flag when the Racing Bull of Arvid Lindblad also crashed out 10 laps from the end after tangling with the McLaren of Oscar Piastri.
Antonelli sat tight in third as Hamilton continued to press Verstappen.
It was entirely appropriate that the young Italian, in tears as he crossed the line, was led in by two of the all-time great drivers with 11 championships between them. (AFP)
