Castelo Branco Municipality (Portuguese pronunciation: [kɐʃˈtɛlu ˈβɾɐ̃ku]) is located in Castelo Branco District, in Centro Region, Portugal. The name means "white castle". It contains the city of Castelo Branco.

The city of Castelo Branco is made up of one parish with a population of 30,649 and the municipality has a total of 25 parishes and 56,001 people. It is one of the largest municipalities in Portugal with 1,439.94 km² and is bounded in the north by the municipality of Fundão, in the east by Idanha-a-Nova, in the south by Spain, in the southwest by Vila Velha de Ródão, and in the west by Proença-a-Nova and Oleiros.