Antonelli needs only a ninth-place finish at the Autodromo Hermanos Rodriguez on Sunday to become Italy's first champion since 1953. He was fifth fastest in qualifying, when he admitted he felt tense, but will move up a place due to Red Bull's Max Verstappen, in fourth, taking a grid drop.
The pole, in a time of one minute 16.514 seconds, was a record-extending 105th of Hamilton's stellar career. While he has had two sprint poles since he joined Ferrari last year, he has not had one at a regular Grand Prix since Hungary in July 2023 when he was at Mercedes - a wait of 1,197 days.
"Thank you so much, it has been such a long time coming," Hamilton said over the team radio. "Mega job, guys - I am so grateful for the hard work you guys put in."
Oldest pole sitter since 1982
The pole also made the seven-times world champion, 41, the oldest pole sitter since American Mario Andretti, at 42, at Monza in Italy in 1982.
Mercedes' George Russell, Antonelli's closest rival but 123 points behind his teammate with only 100 to be won after this weekend, was second fastest - just 0.009 adrift after taking provisional pole only for Hamilton to beat his time - and Ferrari's Charles Leclerc third and 0.119 off the pace.
Both Hamilton and Russell have to win if either of the remaining contenders is to keep Antonelli waiting another week for the inevitable.
"I struggled to get a good feeling from the tyres in Q3. I just didn't have the most confidence. I was a bit tense, I am not going to lie," the Italian said. "It was a poor lap, too many mistakes.
"It has not been the easiest weekend. There is talk of what is there and I am not as relaxed."
McLaren's Lando Norris, the reigning champion and last year's winner in Mexico, qualified sixth with Red Bull's Isack Hadjar seventh.
Racing Bulls' Liam Lawson qualified eighth fastest but with a one-place grid drop for the clash with Verstappen in Friday practice.
The New Zealander was then disqualified from the session for a technical breach and sent to the back of the grid. Teammate Arvid Lindblad will start eighth, Alpine's Pierre Gasly ninth and Audi's Nico Hulkenberg 10th.
"I went to see Max (Verstappen) this morning to apologise because what happened doesn't need to happen and I don't want it to happen in future," said Lawson.
Piastri fails to make top 10
Antonelli was only seventh in the second phase, with Norris fastest and teammate Oscar Piastri knocked out in 13th place in a blow for McLaren's hopes of edging back in front of Red Bull in the battle for third overall.
The Australian complained of lack of rear grip after being told he was out of the top 10.
Aston Martin's Fernando Alonso halted the first session when the team told him to stop in the stadium section with a suspected water pressure issue in the power unit.
The Spaniard was then noted for a general safety incident after he failed to reattach the steering wheel after getting out of the car Hamilton was fastest in that first session, with Antonelli only ninth.
Japanese Ryo Hirakawa, making his F1 race debut this weekend at the age of 32 and in place of Esteban Ocon who was dropped by the team for undisclosed reasons not related to illness, qualified 19th for Haas.
Mexican Sergio Perez, preparing for his 300th Grand Prix in front of his home crowd, and Cadillac teammate Valtteri Bottas filled the back row.
