Brunei-Muara is a district (daerah) of the Sultanate of Brunei. With an area of 571 square kilometers, it is the smallest, but with 292,705 inhabitants the most populous district in the country. Bandar Seri Begawan, the state capital, is also the capital of the district.
The district borders the South China Sea in the north, Brunei Bay with the Brunei River in the east, the Tutong District in the west and Malaysia in the south.
Economically, the district is heavily dependent on the port of Muara.