Formula One's man of the moment continued his dazzling form under the thousands of bulbs that light up the Marina Bay Street Circuit to see off Lewis Hamilton's late salvo by just 0.191 seconds.
Sebastian Vettel had been on provisional pole, but he was forced to abort his final run and will start from a disappointing third, with Hamilton splitting the Ferraris.
Leclerc will now be the favourite to secure his third consecutive victory with every pole-sitter, bar Vettel two years' ago, going on to take the chequered flag here.
Red Bull driver Max Verstappen lines up from fourth with Valtteri Bottas fifth for Mercedes.
Ferrari's machinery was not expected to suit this slow-speed venue, but Leclerc's fine performance provides them with every chance of securing their third win since the summer break.
Hamilton complained about the balance of his car following his first assault on pole and crossed the line one second off the pace. But the world champion delivered an impressive time with his final throw of the dice to be in contention for victory tomorrow.
"I am extremely happy about today," said Leclerc. "It was a very good lap but there were some moments where I thought I lost the car, but I got it back.
"We came here knowing that it would be a difficult track for us but the team has done an incredible job to bring the package we needed. I had a tough Friday, it was not my day, and I didn't feel comfortable in the car, but the hard work has paid off."
Hamilton added: "I don't know where Ferrari picked up their pace today. Charles put some great laps in and it needed something special in the end.
"It was as much as I could get out of the car but I am happy to be on the front row and in the mix with them so we can divide them. We can be aggressive tomorrow."
Vettel looked on course to secure his first pole since the Canadian Grand Prix in June, but an underwhelming final lap saw him drop to third, two tenths off the pace of his team-mate.
"I cannot be happy with that last lap," he said.