The 2012 champion was first on court in the main stadium at Roland Garros and needed little more than an hour to reach the second round by beating Ksenia Pervak 6-1, 6-2.
"It's always nice to get out there on a day like this. It's good to play first match, as you know," Sharapova said. "Hopefully you'll be able to finish the match today with the weather conditions being as they are. It's always nice to get through."
Sharapova broke Pervak five times and finished with 17 winners, while Pervak had only four.
Sharapova, seeded seventh at the French Open, completed a career Grand Slam at Roland Garros two years ago. She then lost to Serena Williams in the 2013 final.
Up next in Paris will be Tsvetana Pironkova of Bulgaria in the second round. But she could face Williams in the quarterfinals.
"It's tough to think about that match down the line where you have to compete in three matches before that," Sharapova said. "Obviously it's a match that many people always look forward to when we play against each other."
Monday's match started about 1 hour, 20 minutes late because of the wet weather. The forecast calls for more rain Monday, and for the rest of the week.
Australian Open runner-up Dominika Cibulkova of Slovakia also advanced, beating Virginie Razzano of France 7-5, 6-0.
Other winners include No. 12 Flavia Pennetta of Italy and No. 16 Sabine Lisicki of Germany. Pennetta beat Patricia Mayr-Achleitner of Austria 6-2, 6-2, while 2013 Wimbledon runner-up Lisicki defeated Fiona Ferro of France 6-1, 7-5.
Information from The Associated Press was used in this report.
Sharapova Routs Pervak
Maria Sharapova beat Ksenia Pervak in straight sets to advance to the second round of the French Open.
Sharapova: Start On Good Note, End On Better One
Pam Shriver talks to Maria Sharapova about the wet conditions and her first-round victory over fellow Russian Ksenia Pervak.