Vettel already leads Alonso by 46 points and will be confident of moving further clear of his rivals, given that Alonso starts Sunday's race from fifth on the grid and Lewis Hamilton — who is third overall in the title race — from a lowly 12th.
"The car was fantastic, better than what we could expect. We had a strong pace yesterday and we were able to take that into qualifying," Vettel said. "This year we're obviously in strong position. We're able to match other cars down the straight and we know that in corners we have a strong car."
Five of the past six winners — including Vettel in 2008 for Toro Rosso and 2011 for Red Bull — have started from pole, and such is the speed Vettel showed on Saturday and Friday that it appears only a mishap will stop him from securing his sixth win this season.
"We've seen in the past that a lot of things can happen," Vettel said, referring to Sergio Perez's second place last year from 12th on the grid. "Race pace is very important, but today we did our homework."
It was Vettel's fourth pole of the campaign — the first since the Canadian GP in June — and 40th of his career. He shares the front row with Red Bull teammate Mark Webber.
"Bit of a surprise to have both cars on the front row in a place where historically we've had bad years," said Vettel, whose 2011 triumph is Red Bull's only podium at Monza. "Hopefully we'll have a good race tomorrow, too."
Webber, who retires from F1 at the end of the season, competes for the last time in Europe.
"I said to the boys I was looking for a qualifying PB (personal best)," the Australian said. "It hasn't been the best place for me, so it's a nice step toward a good result."
Alonso needed a strong performance but finished fifth behind his Ferrari teammate Felipe Massa and Sauber's Nico Hulkenberg, who was a surprising third.
"I didn't expect it especially after a very difficult Friday," Hulkenberg said. "The guys have done a fantastic job to turn the car around and give me such a competitive car."
It was Hamilton's worst qualifying since last year's Spanish GP, while Kimi Raikkonen also recorded his poorest qualifying run this year for 11th.
Hamilton, last year's winner from pole, took the Parabolica turn too wide on the left. After his Mercedes went into the gravel, he was unable to generate any speed.
"That's the worst I've driven for a long, long time. I'm sorry to the team," Hamilton said. "I just didn't drive well."
Vettel was in top form as he posted the leading time in Q1 and then Q2, with his team saying "right Sebastian, that's quick enough" over race radio.
The German earned the first of his 31 career victories in Monza and won here from pole two years ago. Rain is expected for Sunday and that may be his rivals' best hope.
Vettel clocked the fastest time in the morning's third and final practice — ahead of Alonso — having also been best in Friday's second practice.
Frenchman Romain Grosjean, who struggled with the grip in the third practice, locked his front wheels and qualified 13th on a poor afternoon for Lotus.
Alonso has also won the race twice — for Ferrari in 2010 and for McLaren in 2007 — but was wobbling all over toward the end of Q3 and appeared to berate his team over race radio, although the Spaniard later played down the incident.
He has not qualified higher than third all season and will now be up against it on a Monza track regarded as the quickest in F1. Ferrari has given him two races — here and Singapore in two weeks' time — to close the gap before they abandon their hopes and start focusing on developing next year's car.
To beat Vettel, and delight the thousands of Ferrari tifosi, he needs to match Rubens Barrichello's win from fifth spot on the grid in 2009.