Former world number one Osaka came through against her 45th-ranked French opponent 7-6(2), 6-1.
It was Osaka's first win against a top-50 opponent on clay since beating Victoria Azarenka at the French Open in 2019.
Osaka, now ranked at 173 in the world after taking a break from the tour to have her first child, will face 19th seed Marta Kostyuk of Ukraine for a place in the third round.
Kostyuk, the runner-up on clay in Stuttgart last month, lost to Osaka in their only other previous meeting, in three sets at the 2020 US Open.
On Wednesday, the Japanese star sealed victory in 84 minutes, finishing with 27 winners, including eight aces, and broke serve four times.
"I thought the first set was really tough. I'm really glad I was able to close it in two," said Osaka after just her second win on European clay this spring.
"Overall I think mentally I tried to stay as strong as I can, so I'm really happy about that."
She added: "I was up 5-3, serving for the set and I lost (the game). But just being able to hang in there and eventually close it on my terms is something that I'm very proud of myself for.
"I obviously played a lot better in the second set. I'm hoping that when I play my match tomorrow, I want to learn from the mistakes I did today."
