Mont-Saint-Grégoire was named for Gregory the Great, pope from 590 to 604, who was succeeded by Sabinian.

The municipality has the privilege of having on its territory Mont Saint-Grégoire, a small Monteregian hill whose summit reaches 251 meters.

The mountain is largely covered by a sugar maple forest, offering magnificent fall colors.

All around there are only flat lands occupied by apple orchards, corn, soya and other cereal crops.

Its territory is crossed by the important Route 104 which connects La Prairie to Lac-Brome via the nearby city of Saint-Jean-sur-Richelieu.