Mauresmo now meets defending champion Kim Clijsters of Belgium, who came back from a set and a break down to defeat American Jennifer Capriati 4-6 6-3 6-0.
"It's one of my biggest wins, the way I finished it off and handled the loss of the second set against a top player like Justine," Mauresmo said.
"It's one of the best wins emotionally. It shows me that I am capable of great things and some great heart on court."
Twice Grand Slam champion Henin-Hardenne, who secured the year-end number one ranking by reaching the semi-finals here, was fighting a sinus infection and had few answers to her charged-up opponent's attacking style.
Mauresmo needed four match points to clinch victory but finally went through when she charged the net and forced Henin-Hardenne into a backhand error.
"I gave everything I had but wasn't able to win," the Belgian told reporters. "She played well, came to the net and served well.
GREAT PLAYER
"I had my chances but she always came back. She's a great player. She can be number one someday."
In a sloppy affair in which neither woman could find consistency with her groundstrokes, Capriati lost control against Clijsters after taking a medical timeout to treat the right hip problem she has suffered with all week.
The timeout came after she had broken Clijsters's serve to go 3-2 up in the second set.
Capriati made a fast start to the match, immediately breaking serve, but Clijsters broke back to 2-2.
Capriati cleverly manoeuvered her opponent around the court, waiting for Clijsters to make errors, and went on to take the set after breaking serve again in the ninth game.
At the beginning of the fifth game of the second set, Capriati called for the trainer but had to wait until the changeover to receive treatment.
The American still managed to break Clijsters when the Belgian missed an easy backhand volley.
But, after receiving treatment, Capriati lost the power and consistency on her strokes. Clijsters broke to 3-3 and the top seed never looked back, winning 10 games in a row to cruise to victory.
"Maybe I made a mistake," Capriati said. "Maybe I shouldn't have called it (the timeout) because I was on such a roll.
"By doing that I guess I broke up my momentum because it gave her time to sit back and gather herself."
