The 26-year-old Frenchman, who reached the last four in 2008, has dropped down the rankings to 119 from a high of seven in 2011.
Compatriot Virginie Razzano, who stunned current world number one Serena Williams in the opening round last year, has also been handed an automatic entry.
The French Open takes place from May 26 to June 9.
Men - Gael Monfils, Marc Gicquel, Nicolas Mahut, Adrian Mannarino, Lucas Pouille, Florent Serra (all France), Alex Kuznetsov (USA), John Millman (Australia)
Women - Virginie Razzano, Aravane Rezai, Claire Feuerstein, Stephanie Foretz-Gacon, Caroline Garcia, Irena Pavlovic (all France), Ashleigh Barty (Australia), Shelby Rogers (USA)
- Sports & Recreation
- Virginie Razzano
- Serena Williams
- Gael Monfils
- Adrian Mannarino