World number two Nadal, who has won the French Open on the other side of town four times but never this event at the Bercy hall, will meet Novak Djokovic for a place in Sunday's final.
The Serbian world number three earlier, ruined Robin Soderling's hopes of making the World Tour Finals in London by beating the Swede 6-4, 1-6, 6-3.
Gael Monfils, seeded 15th, later made sure there would be a French presence in the last four by recovering from a set down to oust 12th seed Marin Cilic of Croatia with a 3-6, 6-4, 6-4 win.
The gifted but erratic Monfils, worried his fans at first with clumsy errors but then stepped up a gear and thrilled a raucous 14,000 crowd with astonishing winners to set up a semi-final against Radek Stepanek.
Czech Stepanek, the 13th seed, qualified the easy way when US Open champion Juan Martin del Potro, who was hampered by an abdominal strain and was trailing 4-0, retired.
Argentine Del Potro, the world number five, who had survived seven match points before Chilean Fernando Gonzalez retired in their third-round match late on Thursday, clearly struggled to move around the court before quitting.
OUTSIDE CHANCE
Spaniard Nadal, who still has an outside chance of finishing the year as number one, had the crowd against him and faced a strong challenge from the powerful Tsonga. But he showed more composure when it mattered.
"I played a lot better today," said Nadal, who struggled in his previous two matches, saving five match points in the first.
"I was really focused all the time and played well at important moments. This is positive and gives me a lot of confidence," he added.
Nadal made very few unforced errors and seized his chances, managing breaks with perfect timing in the 11th game of each set.
The energetic Spaniard underlined his determination by winning his last game to love and finishing with a service winner, putting Tsonga out of the race for the November 22-29 season finale featuring the world's top eight players.
World number 10 Soderling's defeat by Djokovic means the French Open runner-up, like Tsonga, will not go to London and Spaniard Fernando Verdasco grabs the last ticket to the finals.
Djokovic, who beat world number one Roger Federer in the Basel final last week, looked tired at times, notably in the second set, which Soderling took in just 28 minutes.
"It looked tense because physically I didn't really feel 100 percent there," Djokovic said.
"I've been playing more than 90 matches this year and now two weeks in a row so I'm getting a bit tired, it's all normal," he added.