The top-seeded world No. 7 Berdych snuck past a third-seeded 13th-ranked Monfils 6-2, 4-6, 6-3 in just over two hours on the indoor hardcourt at Montpellier's Arena.
Berdych broke for a 5-3 lead in the final set and closed it out in the next game with a resounding ace. The big Czech tallied 12 aces and three service breaks in the big victory, while Monfils settled for 11 aces and only one break in defeat.
"I expected a tough final," Berdych said. "I felt he was the best player on the other side of the draw. It was a close match, decided by one or two points. I'm happy that I was the one to become the champion and get the last break and finish it with my serve.
"It was a great week. It's a nice place to play tennis. I was surprised to come to an indoor tournament with such a high level. It's great to have a title from here."
The 26-year-old Berdych is now 2-0 lifetime against Monfils, who captured this French event the last time it was contested, in 2010.
The 2010 Wimbledon finalist Berdych is now 7-6 in his career ATP finals, while Monfils, who is now a dismal 4-13 in his career finals, dropped to 0-2 in a pair of 2012 title tilts, as he lost to Jo-Wilfried Tsonga in an all-French championship match in Doha last month.
Berdych's first-place check is worth $95,000.