The Red Bull driver, who is 53 points ahead of Ferrari's Fernando Alonso with seven races remaining, clocked a fastest lap of one minute 42:841 seconds around the floodlit Marina Bay Street Circuit.
The German will be joined on the front row by compatriot Nico Rosberg for Mercedes, who was just 0.091 seconds behind. The second row for Formula One's only night race will be occupied by Lotus's Romain Grosjean and Vettel's Australian team-mate Mark Webber.
Vettel admitted starting from pole gave him a huge advantage but refused to accept it meant victory was in the bag. He said: "Pole is the best position to start from as it is tricky to pass on this track but it's such a long race, so there are plenty of opportunities for all of us... we usually get a safety car in this race, too."
Lewis Hamilton will start fifth in the second Mercedes while Alonso languished in seventh, outqualified by Brazilian team-mate Felipe Massa.
Paul Di Resta's wretched second half of the season continued. The Scot starts from 17th after failing to make it through the first 20-minute qualifying session for the fourth time this year in his Force India.
Di Resta said: "We've not given ourselves the best chance, but whether that's good enough to fight through and score points we'll have to wait and see."
Vettel had looked unstoppable since the second practice session on Friday and although he set the quickest time ever around the demanding 23-turn circuit early in the final qualifying round, he had a nervous wait to be sure of pole after gambling that the time would suffice.
"It's a weird feeling to stand in the garage with two minutes to go, it's much worse when you watch the others and there's nothing you can do," the champion said after Rosberg just missed out.
"I was watching the sector times closely. Mark started with a purple [fastest] sector and Nico and Romain then had a purple sector, but fortunately my last sector was strong enough."
The pole position was the 41st of Vettel's career and fifth of the season. With Alonso so far back on a circuit that is notoriously difficult for overtaking, it looks like only a tropical downpour or a series of safety car periods would stand in the way of the German extending his championship lead.
Rosberg was disappointed not to have overhauled the triple world champion on his final flying lap but was delighted with his overall performance.
"It was very close and it was a pity because one-tenth more and it would have been possible," the Mercedes man said. "But second it still a good position we are confident about our race pace so I think a great result is possible."
Like Red Bull and Mercedes, Lotus have a car that suits the rigours of high downforce tracks like Singapore and despite team- mate Kimi Raikkonen nursing a bad back and managing only 13th on the grid, Grosjean drove brilliantly to qualify third.
The Finn has a problem with a trapped nerve. He revealed he almost pulled out after final practice and was still uncertain last night whether he would take part in the race, with reserve Davide Valsecchi standing by.
Raikkonen said: "This morning was very bad. I couldn't really try, so we probably didn't get done what we wanted with the car, but at least we got it on the grid and we'll see what we can do in the race."
Alonso confirmed yesterday he hopes to sign a further contract extension with Ferrari. The Spaniard said: "I've spent the last four races saying I want to stay.
"We are working very closely on arriving at that situation because I hope to end my career in Formula One with Ferrari and the team have expressed to me more or less the same desire."