Ecuador twice took the lead at the ArcelorMittal Park, but France responded on both occasions before Landryna Bilombi struck three minutes from time to complete the turnaround.
Ecuador made the stronger start and opened the scoring in the 10th minute through Dariana Morán, who put the South Americans 1–0 ahead.
France were awarded a penalty in the 21st minute, and Justine Rouquet calmly converted to bring the match level at 1–1.
Ecuador restored their advantage just before half-time when Fiorella Pico converted another penalty in the 41st minute, sending France into the interval 2–1 down.
France responded immediately after the restart. Aude Bizet equalised in the 48th minute to make it 2–2 and set up a tense final period.
The decisive moment arrived in the 87th minute when Landryna Lushimba Bilombi found the net to complete France's comeback and give the European side a 3–2 victory.
• France: Justine Rouquet 21' (pen), Aude Bizet 48', Landryna Lushimba Bilombi 87'
• Ecuador: Dariana Morán 10', Fiorella Pico 41' (pen)
The victory moves France onto four points from two matches after opening their campaign with a 1–1 draw against South Korea. Ecuador, who had beaten Ghana 3–0 in their opening fixture, remain on three points.
The result also leaves Group C finely poised ahead of the final round of matches. France will face Ghana on September 12, while Ecuador will meet South Korea on the same day.
For Ecuador, the defeat was particularly painful after twice holding the lead. Nevertheless, their 3–0 victory over Ghana in their opening match means they remain firmly in contention for qualification from the group.
France, meanwhile, showed considerable resilience to recover from two setbacks and secure what could prove to be a decisive victory in the race for the knockout stages.