Leclerc was 11 seconds clear with seven laps to go and 8.3 ahead with five remaining as the massed ranks of 'tifosi' willed him on.
McLaren are leading the constructor's championship but are only 29 points ahead of Ferrari, with Leclerc an obvious threat and team mate Carlos Sainz qualifying fifth and Mercedes' George Russell sixth.
Red Bull's triple world champion Max Verstappen followed up a Saturday sprint win with a statement pole position for Sunday's Austrian Grand Prix, with McLaren's Lando Norris again alongside on the front row.
The times at the Istanbul Park circuit, hosting a Formula One race for the first time since 2011, were largely meaningless.
Mercedes drivers George Russell and Lewis Hamilton blamed miscommunication for a coming together in Spanish Grand Prix qualifying.
McLaren's Lando Norris dominated the Singapore Grand Prix from start to finish on Sunday to take another chunk out of Max Verstappen's Formula One championship lead.
World champion Max Verstappen took the first pole position of the Formula One season in Bahrain on Friday.
Red Bull's Verstappen, who had been on pole at Zandvoort every year since the circuit returned in 2021 and has yet to be beaten there, will still line up alongside the Briton on the front row.
Mexican team mate Sergio Perez qualified second fastest in a front row lockout for Red Bull, 15 years after the team took their first win at the Shanghai International Circuit with Sebastian Vettel.
Verstappen, who had started alongside Norris on the front row, was leading by lap three and could then build a buffer and take control.
Formula One will have a record 24 races in the season that starts in Bahrain on Saturday.
Formula One world champion Max Verstappen took pole position for a third straight year at the Japanese Grand Prix on Saturday, with Sergio Perez qualifying a close second to ensure a Red Bull front-row lockout.
Images from the Russian F1 Grand Prix in Sochi on Sunday
Charles Leclerc won the US Grand Prix in a Ferrari one-two with Carlos Sainz on Sunday as Formula One championship leader Max Verstappen dealt Lando Norris a significant setback in their title battle.
The front row lockout was a record-equalling 65th for champions Mercedes.
Red Bull are concerned about their constructors' title defence being weakened at a time when McLaren are emerging as a threat
Red Bull's Formula One World champion Max Verstappen took pole position for the Australian Grand Prix on Saturday with Carlos Sainz qualifying alongside on the front row for Ferrari two weeks after undergoing surgery for appendicitis.
Ferrari, whose race on Sunday lasted about 20 seconds until Sebastian Vettel and Charles Leclerc collided, said the team strongly supported diversity and equal opportunities.
After pipping Ferrari's Sebastian Vettel with a lap of one minute 23.599 seconds in the first practice, the Briton shaved almost a second in FP2, his quickest lap clocked at 1:22.60.
World champion Max Verstappen got back to winning ways on Sunday with a third straight pole-to-flag victory at the Japanese Formula One Grand Prix, leading teammate Sergio Perez across the line for a Red Bull 1-2 at Suzuka.
The win was a first for Ferrari in Mexico since 1990 and fourth of Carlos Sainz's career.
Triple Formula One world champion Verstappen missed out on pole because he set his time of one minute 12.000 seconds after his British rival in a drama-filled qualifying session at the Circuit Gilles Villeneuve.
Lewis Hamilton did 94 laps of Barcelona's Circuit de Catalunya on the soft C2 compound in a sunny afternoon session
Red Bull's Max Verstappen dealt Lando Norris a shattering blow in their Formula One title battle by winning a wet and chaotic Sao Paulo Grand Prix from 17th on the grid.
The pole was the 26th of Charles Leclerc's career, and third of the season.
Red Bull make changes to car after discussions with FIA
The pole was a record-extending 88th of Hamilton's career and fifth of the season.
Verstappen took pole position for the Saudi Arabian Formula One Grand Prix on Friday with Ferrari's Charles Leclerc qualifying alongside on the front row.
Television images showed six drivers standing behind the 14 who knelt, including Red Bull's Max Verstappen and Ferrari's Charles Leclerc.
Red Bull's Max Verstappen equalled Ayrton Senna's record of eight pole positions in a row.
Red Bull's Max Verstappen started the season with a commanding Bahrain Grand Prix win from pole position.
Red Bull's triple World champion Max Verstappen wrapped up a year of unprecedented dominance with his record-extending 19th win in 22 races at the season-ending Abu Dhabi Grand Prix on Sunday.
Lewis Hamilton was 'shocked' with the pace of Mercedes after notching a record-extending eighth pole position at the Australian Grand Prix ahead of team mate Valtteri Bottas as they thrashed their Formula One rivals in qualifying on Saturday.
Max Verstappen clinched his second win of the season as the Australian Grand Prix was halted with three red flags.
Max Verstappen held off a late charge by McLaren's Lando Norris to win the Emilia Romagna Grand Prix
Max Verstappen won the Spanish Grand Prix from pole position to stretch his Formula One championship lead to 53 points.
Max Verstappen became the first Formula One driver to take 16 victories in a season
As impressive as those results have been, Red Bull team principal Christian Horner took the opportunity after the race to issue a scary warning that his team is capable of winning every grand prix this season.
Red Bull's Max Verstappen won a rain-delayed and shortened sprint race from pole position at the Belgian Grand Prix on Saturday to stretch his Formula One lead to 118 points.
Red Bull's triple World champion Max Verstappen claimed pole position on Saturday for the Miami Grand Prix, to start from the front of the grid for the sixth straight race this season.
