The first set was a routine affair, Federer dominating his opponent, crafting two break points in each of his first two receiving games, taking both to win it 6-2 at a canter.
The second set looked to be heading the same way when the Swiss skipped into a 4-0 lead once more, but Sonego found a second wind, recovering one of the breaks with some aggressive net play.
Nevertheless, the fightback was short lived and Federer served it out 6-4. In the final set, Federer was forced to be patient for his chance to get on the front foot, but got his chance in the penultimate game of the match and he made no mistake on his own serve.
Highlights: Federer makes winning start
"I missed the French crowd so thanks for the warm welcome today," the 20-time Grand Slam champion said.
"Congratulations to the French Open for the transformation. It's better for the fans, the players, the media. It was great for me to play on this court. Hopefully I can also play on this court in my next match.
"Two breaks in the first set was very important for me and when I was leading 4-0 I could take more risks and play more aggressive. I knew I can play very well on clay and I am very happy I did it in straight sets today."