"It was a great race, the start was very good -- maybe too good and I ended up on the grass," grinned Button, ecstatic at his third win of the season and 12th of his career.
"It's always a very special place to race, Suzuka. This is one of the most perfect places to race and the crowd are very special. It's one of our most special victories, it means a lot to me," added the Briton, who had written off his own title chances long ago.
Just as he had when he won in Monaco in 2009, his title year, Button parked his car in the wrong place and ran back up the pit lane waving to fans.
Alonso had threatened to take the win but Button had just enough in his tyres to keep him at bay. Vettel was only 0.8 seconds further back.
The win cut Vettel's overall lead over the Briton to 114 points, an insurmountable advantage with a total of 100 left to be won.
Image: Red Bull Formula One driver Sebastian Vettel of Germany celebrates after finishing third in the Japanese Grand Prix to clinch the Formula One drivers championship, at the Suzuka Circuit in Suzuka, Japan on Sunday, Oct. 9, 2011.