Gasquet's last trophy came in May 2010 with victory in Nice.
The world number 14 ended the long dry run, however, with an emphatic straight-sets win over an injured Simon, ranked five places below Gasquet.
The indoor hardcourt title was the seventh of Gasquet's career and the easy victory improved his record over Simon to 6-0.
The 250 rankings points will also help improve his chances of reaching the season-ending World Tour finals in London in November for the top eight men.
Fourth-seed Simon started brightly by breaking Gasquet in the opening game before unravelling in the lopsided contest in the Thailand capital with his failure to win points on his serve letting him down.
Simon struggled with his knee throughout and was clearly dejected after the result.
"I'm glad to win a title but it's tough to do it like this against another French player, a friend of mine," Gasquet said after the match.
"I have to be pleased to win but it was a little bit strange.
"I've had some tough matches this week, so this seventh title is a big one for me.
"I've played and lost some finals over the years since my last one, so it's always good to finally win one. It was a good win for me here, a big comeback week."
Runner-up Simon is unsure whether he will be fit to participate in the next event in Tokyo.
"I'll have to see how I feel and how I practice there," he said.
"I was playing some of my best tennis in the semi-finals -- in the final it ends like this.
"It would have been nice to win this one for him [former coach Thierry Tulasne] , but it was not to be," said Simon.
"I just can't be optimistic any more, I just have to live with this kind of uncertainty," said Simon, who has also suffered with back and shoulder problems in recent years.