Mexico City: Kimi Antonelli needed only ninth place on Sunday to be champion. He finished third, and at 20 years and 68 days the Mercedes driver is the youngest world champion in Formula 1 history.
Sebastian Vettel held the record, winning his first title in 2010 at 23 years and 134 days.
Antonelli is also the first Italian to take the crown since Alberto Ascari in 1953, ending a 73-year wait, and only the third Italian champion after Ascari and Giuseppe Farina. He is the first graduate of Mercedes' junior programme to win the drivers' title, the team's 10th.
Max Verstappen won the race for Red Bull, with Ferrari's Lewis Hamilton second. Antonelli's voice cracked on the radio as he crossed the line. "We did it, we did it," he said.
The season numbers are not those of a lucky champion. Mercedes said Antonelli has won nine races this year, six of them before his 20th birthday, and that Sunday was his 17th podium of the season. He came into Mexico with a 123-point lead over team-mate George Russell and sealed the title with four rounds still to run.
The race itself had a stoppage. A sizeable crash for the Cadillac of Valtteri Bottas brought out the red flag, and the restart order, taken from the control line at pit entry, put Antonelli back in fourth. He recovered to third within two laps, passing Charles Leclerc into Turn 1.
The podium that followed was an unusual sight: three world champions, Verstappen with four titles, Hamilton with seven and Antonelli with his first.
Antonelli replaced Hamilton at Mercedes in 2025 and is in only his second F1 season. What comes next is the harder part: doing it again.