Federer, the 2009 champion in Paris, will face German lucky loser Oscar Otte for a place in the third round.
The 20-time major winner hadn't played the tournament since 2015 when he reached the quarter-finals.
However, on Sunday, it was as if the 37-year-old had never been away as he swept to victory in one hour 41 minutes on a rebuilt and packed Court Philippe Chatrier.
It was his 60th successive first round win at a Grand Slam.
"I missed it so much so thanks for the welcome," said Federer.
'On edge' Federer marks Paris return with victory, Kerber crashes
"I felt great playing on this court. It looks great and attractive, so congratulations to everyone involved.
"Hopefully I can play here again for my next match."
Federer broke serve five times and fired 36 winners past 24-year-old Sonego, the world number 73 who made the quarter-finals at the Monte Carlo Masters this year after qualifying.
"Two breaks in the first set was very important for me and when I was leading 4-0 I could take more risks, be more aggressive," said the third seed.
"I know that I can play very well on clay and I am very happy to win in straight sets."
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ