The 24-year-old German, who had started on pole position for the 10th time in 13 races, stretched his overall lead to a mighty 112 points after Australian team mate and closest rival Mark Webber crashed out.
With only 150 points remaining to be won from the last six grands prix, Vettel has now won eight races this season and can clinch the title at the next one in Singapore on Sept. 25 if results go his way.
McLaren’s Jenson Button finished runner-up for the third season in a row at Monza with Ferrari’s Fernando Alonso, last year’s winner from pole, giving the sea of red-shirted fans something to cheer about with third place at his team’s home race.
Vettel, who took his first Formula One win at Monza with Red Bull’s Italian-based sister team Toro Rosso on 2008, let all the emotions flood out on his return to the podium. He now has 284 points to double world champion Alonso’s 172 and Button’s 167.
“When you stand up there you feel so blessed. It doesn’t happen to many people,” said Vettel who swerved across to the pit wall with one finger raised as he crossed the line.
“This circuit means a lot to me...obviously the first one was very special but to be back here...incredible,” he gasped.
“I really had a very, very good race car and a fantastic day today.
“It’s the best podium in the world. The only thing that could make it better is probably wearing a red suit.”
On a sweltering afternoon in the royal park near Milan, Alonso had the home fans leaping in excitement at the start by seizing the lead, roaring past Vettel with one wheel on the grass, from fourth place on the grid.
The Spaniard held his advantage for the first four laps thanks to the safety car, which had to be deployed immediately after Italian Vitantonio Liuzzi lost control of his HRT, skidding across a corner and slamming into Vitaly Petrov’s Renault.
Germany’s Nico Rosberg was also caught in the mayhem, retiring his Mercedes on the spot.
McLaren’s Lewis Hamilton finished fourth after a thrilling battle with the old master Michael Schumacher, a five-times winner at Monza in his glory days with Ferrari, and then striving in vain to catch Alonso over the closing laps.
Schumacher gave no quarter, his defensive driving prompting a frustrated Hamilton to question whether the seven-times champion’s moves were legal.
That triggered a veiled warning from Mercedes team boss Ross Brawn to Schumacher, reminding him to leave enough space at the Ascari chicane.
While Hamilton and Schumacher tussled, Button caught them both napping and passed in quick succession.
“I don’t know if we could have challenged Sebastian today... it’s a pity we had such a poor start,” said Button, who qualified third but was sixth at the end of the first lap.
Schumacher, with plenty of fans in the throng of flag-waving tifosi flooding on to the finish straight for the podium celebrations, finished fifth ahead of former Ferrari team mate Felipe Massa.
For the first time in Formula One, the top five finishers were all world champions.
Massa was the last unlapped driver, on a day when only 15 of the 24 starters finished at the fastest circuit on the calendar, and was lucky to escape with an undamaged car after tangling with Webber.
Webber, who had started the day second overall, tried to pass Massa on lap five but hit the back of the Ferrari and lost the front wing, which became wedged under the car. He then crashed into the tire wall at Parabolica.
“I think we are all battling for second place now,” he said of the championship.
Spain’s Jaime Alguersuari was seventh for Toro Rosso and Britain’s Paul di Resta, of Italian descent, eighth for Force India.
Brazilian Bruno Senna, nephew of the late triple champion Ayrton, scored his first points in Formula One with ninth place for Renault and Swiss driver Sebastien Buemi claimed the final point for Toro Rosso.
