Leclerc had led his teammate Carlos Sainz ahead of the final laps in Q3, with his 1m11.376s the benchmark time for pole.
Perez looked to be Red Bull’s best hope for pole after topping FP3 and leading Max Verstappen throughout qualifying and he trailed Leclerc on the final fliers on the soft tyres, the second set for the top three runners in the final segment.
Leclerc set a purple sector in the opening third of his final effort – he ended up with the quickest time in all three based on his 1m11.376s lap – while the following Perez could not reproduce a personal best at that point.
While Leclerc was exiting the tunnel, Perez lost the rear of his Red Bull and smashed the right rear of his car against the barriers at the exit of Portier, after which Sainz also spun when he came around the right hander and found the wrecked Red Bull .
Sainz therefore struck the right front wheel of Perez’s car and was also stranded, with the red flags flying and preventing any late improvements or position changes as there was less than a minute of Q3 remaining and no chance of it being restarted.
That cemented Leclerc’s second Monaco pole in a row, with Sainz’s best time from the start of Q3 putting him 0.225s adrift, with Perez third thanks to his 1m11.629s.
Verstappen ran one set of softs throughout as he opted to continue chasing time to the flag, ending up fourth and unable to improve – he had just set a personal best in the first sector that was 0.1s down on Leclerc’s leading time there – because of his teammate’s incident.
Lando Norris slotted into fifth just before the leaders began their final lap, with George Russell sixth for Mercedes.
Alpine’s Fernando Alonso took seventh, but he too had a late crash, ending up in the barriers at Mirabeau at nearly the same time as Perez and Sainz were crashed further down the hill in sector two.
Lewis Hamilton ended up eighth, with Sebastian Vettel and Esteban Ocon rounding out the top 10.
Leclerc led the session’s middle segment, which featured a worrying moment for the Ferrari driver as he missed his call to visit the FIA weighbridge with just over five minutes of Q2 remaining.
Fortunately for Leclerc he stopped in the pitlane before returning to his garage and so could be pushed backwards by his mechanics to be weighed, the result of which should mean he does not receive a sporting penalty, as returning to the Ferrari pits risked a qualifying disqualification .
At the end of Q2, Yuki Tsunoda failed to produce a personal best when it mattered and he was eliminated in 11th.
Valtteri Bottas jumped from 15th to 12th on his final run, with Kevin Magnussen and Mick Schumacher also their quickest times of the session on their final fliers behind.
They ended up 13th and 15th, sandwiching McLaren’s Daniel Ricciardo, who also set a personal best at the end of Q2 but could do no better than 14th.
In Q1, which Leclerc also topped, Tsunoda clipped the inside wall at the hairpin and picked up an immediate puncture with just over two minutes of that segment remaining, with the red flags flying as a result.
That led to a huge queue at the end of the pitlane as the drivers below the top five at the time rushed out to try and secure one final lap, with track evolution a major factor in who progressed through the early sessions as rubber went down and the drivers built confidence.
But gaps emerging between the cars in the long snake leaving the pitlane meant several drivers missed out on a chance to even start a final flier, with Pierre Gasly and Zhou Guanyu eliminated in 17th and 20th as a result – the former banker’s effort slowly shuffled down the order until Tsunoda’s AlphaTauri teammate was knocked out with the chance to post one last effort.
Alex Albon had headed the cars that queued at the end of the pitlane and managed to post a personal best with his final lap, but was subsequently pushed down as others behind found time.
This was particularly the case with the Tsunoda and the two McLaren drivers, who all jumped out of the drop zone with their final Q1 laps to leave Albon 16th and out.
Lance Stroll could not post a better time on his last Q1 run and was dumped out, screaming down his team radio, in 18th, ahead of Nicholas Latifi, who did save his best for last but could do no better than 19th.