Tsonga produced a stunning display of serving and shot-making in the 6-3, 4-6, 6-4 win that made him the first Frenchman since Sebastien Grosjean in 2001 to win the indoor tournament.
"I think tomorrow I'll be in some pain, especially after the party I'm going to have," Tsonga said.
The 23-year-old Tsonga's second career title gave him the eighth and final spot in the ATP race and a spot in the season-ending Masters Cup in Shanghai next week.
"I think the Masters will be a very important moment for me," Tsonga said. "Maybe another great victory could replace this one. Why not? I'm going to give my best."
Tsonga lost the Australian Open final to Novak Djokovic, but beat him in Paris, and in the final in Bangkok for his first career title last month.
Nalbandian's form dipped at the wrong time against Tsonga.
"I think he served better than me and that was pretty much the key of the match," Nalbandian said. "I didn't play badly, but I didn't play like the other days. I couldn't move naturally."
"I was playing with 15,000 people. Everybody was behind me today. The crowd was magic," Tsonga said. "Sometimes I had to calm them down because I was perturbed. It was so fabulous."
Tsonga broke Nalbandian's serve for a 2-1 lead in the deciding set, and saved a break point in the sixth game with an ace.
Nalbandian's frustration showed in the eighth game when he slammed his racket to the ground. But he kept his composure to hold serve in the ninth game and then had Tsonga down 0-40. However, Tsonga saved all three break points, then hit an ace to set up match point and get the crowd on their feet.
Tsonga's first serve flew into the net, but his second pinned Nalbandian to the back of the court and he went on to win the resulting rally.
Tsonga will join seven other players in Shanghai, starting Nov. 9, while Nalbandian missed his chance to qualify.
"He's a great player and has played brilliantly all week," Nalbandian said. "He deserves this title."