Mladenovic was too powerful for Kvitova, a former winner of the tournament, firing six aces to Kvitova's one en route to a 6-3 6-4 victory.
Kvitova has struggled for form in 2013, but there was no sign of nerves from the French starlet in front of her home crowd as she broke to love to seal the match.
Mladenovic was not alone in continuing a breakthrough run in Paris - unheralded Dutch starlet Kiki Bertens dumped out sixth seed Lucie Safarova to join her in the last four.
The 21-year-old, who scored her first victory over a top 20 opponent yesterday by ousting Dominika Cibulkova, blasted her Czech opponent off the court 6-1 in the first set, before edging a tighter second 7-5.
Bertens will next face top seed Sara Errani, who extracted some revenge by defeating Carla Suarez Navarro in a three-hour duel.
Navarro had overcome the Italian in the first round of the Australian Open last month, one of the biggest early shocks in Melbourne. She was again a fierce competitor, but Errani held her nerve to triumph 7-5 4-6 7-5.
But hopes of an all-French semi-final were quashed when Marion Bartoli, seeded three in Paris, was edged out in straight sets by Mona Barthel of Germany.
Kristina Mladenovic (France) beat 2-Petra Kvitova 6-3 6-4
1-Sara Errani (Italy) beat Carla Suarez Navarro (Spain) 7-5 4-6 7-5
Kiki Bertens (Netherlands) beat 6-Lucie Safarova (Czech Republic) 6-1 7-5
Mona Barthel (Germany) beat 3-Marion Bartoli (France) 7-6(7) 6-4