"We carried out strikes in Ramadi and Mosul in support of ground forces that were pushing against troops of (the Islamic State group)," said army chief of staff General Pierre de Villiers, aboard the carrier.
He said planes from the Charles de Gaulle would launch strikes against IS targets in Syria, including command and recruitment centres as well as oil facilities, in "a matter of hours or days".
Rafale jets catapulted from the carrier's flight deck on Monday morning, an AFP reporter saw.
French President Francois Hollande said earlier in Paris: "We will intensify our strikes, choosing targets that will do the most damage possible to this army of terrorists."
The Charles De Gaulle has 26 fighter jets, more than trebling France's strike capacity in the US-led mission against IS.
France already has six Mirage and six Rafale jets stationed in the United Arab Emirates and Jordan.
A military source said their missions would overfly Turkey or Jordan to avoid Syrian anti-aircraft defences.
To avoid crossing paths with Russian planes, France is coordinating with Moscow via the US coalition headquarters in Qatar.
Russian President Vladimir Putin instructed his navy last week to work with the French "as allies".
After its operation in the Mediterranean, the Charles de Gaulle will head to the Gulf to relieve a US carrier.
