[1] The municipality is named after the adjacent Lake Saguay, which in turn comes from the Algonquin sagwa, meaning "unblock" or "pour".

[4] In 1911, the Township Municipality of Boyer-Partie-Ouest was formed out of previously unorganized area, named after Arthur Boyer.

[1] On July 1, 1951, Boyer-Partie-Ouest was dissolved and, together with more unorganized territory, reformed into the Township Municipality of Boyer.

[3] Mother tongue (2021):[3] Lac-Saguay forms part of the federal electoral district of Laurentides—Labelle and has been represented by Marie-Hélène Gaudreau of the Bloc Québécois since 2019.

Provincially, Lac-Saguay is part of the Labelle electoral district and is represented by Chantale Jeannotte of the Coalition Avenir Québec since 2018.