The municipality is located in a densely wooded area on the shores of Lake Brompton.

The region was still little frequented at the beginning of the 19th century when the township of Brompton was proclaimed in 1801 on the lands of the county of Buckinghamshire.

French is the primary language spoken in Saint-Denis-de-Brompton, though some people, especially those who deal often with tourists, are able to speak and understand English.

Saint-Denis-de-Brompton forms part of the federal electoral district of Richmond—Arthabaska and has been represented by Alain Rayes, an independent MP, since 2015.

Provincially, Saint-Denis-de-Brompton is part of the Richmond electoral district and is represented by André Bachand of the Coalition Avenir Québec since 2018.