The Frenchman is ranked down at 240 after a run of poor form and injury, and needed to come through qualifying to reach the main draw of the Topshelf Open.
Mahut, most famous for his epic loss to John Isner at Wimbledon three years ago, is a specialist on grass and he showed his prowess on the surface in Saturday's 6-3 6-4 victory over second seed Stanislas Wawrinka.
The 31-year-old's only dropped set in the tournament came in his final qualifier against Lukas Kubot and he will head into his first-round match at Wimbledon against Czech Jan Hajek in high spirits.
Mahut, who has been given a wild card for Wimbledon, said on www.atpworldtour.com: "It's amazing. I cannot believe I won today [Saturday].
"I didn't know if I was going to play again when I had some bad times with my knee. All my team helped me a lot. We worked hard and here I am with the trophy. It's a good story."
Another player heading for the All England Club full of confidence is Romania's Simona Halep after she made it back-to-back titles on the WTA Tour in the women's event.
Halep lifted the trophy in Nuremburg on clay last week and did the same on Saturday, beating fourth seed Kirsten Flipkens 6-4 6-2.
"It's incredible, because I played really well on grass after a week on clay," said Halep on www.wtatennis.com. "I'm really happy. I want to enjoy this evening [Saturday]. It's a special moment for me."
The 21-year-old faces Olga Govortsova in the first round at Wimbledon and could be a tough second-round opponent for sixth seed Li Na.