Vettel's time of 1:24.119 put him over three quarters of a second clear of next-quickest Nico Rosberg.
Fernando Alonso, who needs a miracle collapse by Vettel to keep his chances of the title alive, also gambled on the medium tyre but could only qualify eighth.
The Spaniard's Ferrari team-mate Felipe Massa took fifth, followed by Kimi Raikkonen and Nico Hulkenberg for Lotus and Sauber respectively, while the day's big loser was Lotus's Romain Grosjean, whose attempt to get out of Q1 using only the slower medium tyre backfired as he failed to make the top 16 with a string of untidy laps.
McLaren used mediums for both its drivers as Sergio Perez and Jenson Button completed the top 10.
Alonso's strategy was sound: he needed to pursue a different strategy to Vettel to have any realistic chance of keeping the title alive. With soft tyres lasting just 8-10 laps in India, any drivers starting on the softs will have to pit in the very early stages of the race, thus giving a potentially great advantage to drivers starting on the medium tyres.
But Red Bull clearly realised what Alonso would be doing, and ensured that Webber followed the same strategy as the Ferrari to ensure that they will control the race no matter what happens.
"We split our options and don't know which is the better route," admitted Red Bull chief Christian Horner after qualifying, adding that he had told Webber before the session that starting in the top six but on the harder tyre would be as good as starting from pole position.
"We decided to go for what I did, and Mark decided to go for the opposite," said Vettel. "What turns out to be the right strategy we'll find out tomorrow.
"But the race is long and you will have plenty of time to make it up. The strategy should not determine the result that much.
"We have good pace and the car behaves well around here, so we will see what we can do."
Such arguments are likely to be a moot point following this weekend: Vettel is 90 points ahead in the championship, and almost certain to clinch the title in India. A fifth place would be enough for Vettel to win the title, and even that is only needed should Alonso finish first. If Alonso is second then Vettel can come eighth and still win the title.
"I am trying not to think about it," Vettel added when asked about the title.
"It is difficult when every second person in the paddock asks you the same question.
"We have done very well in the past focusing on every single step, and we see no reason to change things for tomorrow or the next couple of races.
"We have a good position and we have worked hard to be there."
Nico Rosberg said it all about Vettel's dominance when he explained the lengths he'd had to go to in order to claim second place on the grid.
"I am completely on a knife's edge, really pushing to the limit, trying to extract that tenth more out of the car," said Rosberg, who had last started from the front row in Singapore.
"Qualifying second was better than I hoped for because of Mark [Webber] being on another strategy. The race is going to be tough."
Lewis Hamilton was similarly philosophical about the Mercedes' chances.
"I've struggled with something different on the car this weekend which Nico had experienced in the past," he said.
"I'm happy with the result and laptime I could get. We will try to push these guys as much as possible but they are in another world and we will try to be the best of the rest."