La Pallaide lifted their first ever league title on Sunday night after a 2-1 victory over Auxerre.
Paris Saint-Germain could only finish in second place, despite spending big money since being taken over by Qatar Investment Authority last summer.
Girard said that Montpellier's triumph is a "shot in the arm" for French football.
"I'm so proud of my players, who have produced a remarkable season," said Girard. "We played well, scored a lot of goals, didn't concede many. We deserved to go all the way.
"Our supporters have been exceptional. I hope we're going to have the most incredible party with them back in Montpellier. I take my hat off to the fans - there are some strong bonds being made between the team and the fans this season.
"I think our triumph is a real shot in the arm for French football. It just goes to show that everyone can beat everyone and that money isn't the be-all and end-all. We're a club of mates, a club that brings young players through and gives them a chance. At the end of the day, it's worked out well for us. We played some great football, with a well-balanced team and I'm overwhelmed."
Girard won the Ligue 1 title three times as a player for Bordeaux.