Map - Kuala Belait (Kuala Belait)

Kuala Belait (KB; Jawi: ) is the administrative town of Belait District, Brunei. The population of the town proper was 4,259 in 2016. Kuala Belait is officially a municipal area (kawasan bandaran), as well as a village under the mukim of the same name. The town is located 85 km west of the country's capital Bandar Seri Begawan, and 20 km west of Seria, the district's other town. It is also in the westernmost part of country, near the mouth of the Belait River.

In 1914, a 60 mi road connecting Kuala Belait and Brunei Town was completed. Kuala Belait was a small fishing village at the turn of the 20th century. The natives were Belait Malays who were mainly fishermen. There was a disagreement between the two groups of settlers which caused one of those groups to the relocated up to the west bank of the mouth of the Belait River. The village is now known as Sungai Teraban.

The Kuala Belait Sanitary Board was established in 1929, and this marked the transition of Kuala Belait from a village to a town. In 1930, British Malayan Petroleum Company (BMPC) constructed a telephone line along the Belait coastline which linked up Seria and Rasau with their main headquarters in Kuala Belait. A hospital was built by BMPC and completed in 1931, followed by the first private English school being built that same year. Telephone lines stretching from Kuala Belait to Tutong was dismantled in 1934 after failing to meet expectations. By 1939, pipelines and roads between the town and Miri has been constructed. On December 16, 1941, the town was captured after an amphibious assault was carried out at Belait Beach by 10,000 soldiers from the Japanese Kawaguchi Detachment and remained part of the Japanese occupation of British Borneo during World War II. Moreover during the Japanese occupation of Kuala Belait, war crimes such as massacre and execution of Indian prisoners of war (POW) of the 2/15th Punjab Regiment were committed out by the Japanese. It can also be noted that 55 Indian prisoners died from starvation in the POW camp in town. As part of Operation Oboe Six, the Australian 9th Division arrived in Kuala Belait on June 24, 1945, followed by the recapturing of the port of Kuala Belait. Reconstruction plans for the destroyed town were approved in 1949. Within the same year, a new church in town was consecrated.

Due to the increase in profits from the oil industry in the 1950s and 1960s, rapid development was seen throughout Kuala Belait. The first offshore gas field, South West Ampa, was discovered 13 km off Kuala Belait in 1963. During the 1962 Brunei revolt, rebels of the TKNU managed to gain control of the town, but was soon liberated by the 1/2nd Battalion Gurkha Rifles Regiment. Siege by the rebels against the town's police station were repelled by the local police force. After independence from Britain in 1984, a number of new government buildings were constructed to house the local services of the Brunei government. In 1990s, the two-lane road along the coast leading from Muara to Kuala Belait was upgraded to 4-lane.