Brønnøy is a municipality in Nordland county, Norway. It is part of the Helgeland region. The administrative centre and commercial centre of the municipality is the town of Brønnøysund. A secondary centre is the village of Hommelstø. Other villages include Tosbotnet, Lande, Trælnes, and Skomo.
The 1,046-square-kilometre (404 sq mi) municipality is the 107th largest by area out of the 357 municipalities in Norway. Brønnøy Municipality is the 135th most populous municipality in Norway with a population of 7,826. The municipality's population density is 7.5 inhabitants per square kilometre (19/sq mi) and its population has decreased by 0.9% over the previous 10-year period.