The 11th seed beat former champion Svetlana Kuznetsova 7-6 6-4 and shrieked in delight when she ended the contest on her second match point.
Bartoli, who was runner-up at Wimbledon in 2007, will now face holder Francesca Schiavone for a place in Saturday's showdown.
After benefiting from the crowd support to prevail on Tuesday, and she intends to do just that again on Thursday.
"The crowd, the (Mexican) wave, they were calling my name... they were supporting me. I was just like, 'My God, I'm in the semi-final of my home grand slam'. Finally I can play well here," Bartoli said.
Mary Pierce, the 2000 champion, was the last Frenchwoman to reach the semis at Roland Garros six years ago while former Australian Open and Wimbledon winner Amelie Mauresmo never lived up to expectations in Paris.
On Tuesday, Bartoli was determined not to let the occasion get to her.
She won the opening set tie-break 7-4 after both players conceded three breaks each. Bartoli then outraced the 13th-seeded Kuznetsova in the second set to seal the win when her opponent returned wide after one hour 53 minutes.
"The past years I really felt the pressure here. I mean in a bad way. I was really going to the court without any confidence, to be honest," she said.
"I was not feeling well on the court. I was not feeling well outside the court. I was scared about what the press would say when I'm gonna lose the match or whatever.
"I really thought that this year I should try to take some pleasure, even though it's difficult, because, of course, we are French and we want to do well," she explained.
"I told myself, 'If you use that crowd, if you use that to put some pressure on your opponent, maybe you can do well'."