Tlass was reported to have fled Damascus earlier this month, but it's the first time his presence in France has been confirmed by authorities.
Hollande nodded when asked if Tlass was in the French capital during a press conference with Tunisian President Moncef Marzouki, but he did not specify where in Paris he was staying.
Syria is caught up in a civil war brought about after President Bashar Assad violently cracked down on a popular uprising that began 16 months ago. Activists say the conflict has killed more than 17,000 people.
Tlass was a confidant of Assad and son of a former defense minister. His defection buoyed Western powers and anti-regime activists, who expressed hope that other high-ranking defections would follow.
Last week, Syria's ambassador to Iraq, Nawaf Fares, followed suit and defected, announcing that he was joining the revolution.