Historians believe there was a forerunner to the present Brunei Sultanate, which the Chinese called Po-ni. Chinese and Arabic records indicate that this ancient trading kingdom existed at the mouth of the Brunei River as early as the seventh or eighth century A.D. This early kingdom was apparently conquered by the Sumatran Hindu empire of Srivijaya in the early ninth century, which later controlled northern Borneo and the Philippines. It was subjugated briefly by the Java-based Majapahit Empire but soon regained its independence and once again rose to prominence.

The Brunei Empire had its golden age from the 15th to the 17th centuries, when its control extended over the entire island of Borneo and north into the Philippines. Brunei was particularly powerful under the fifth sultan, Bolkiah (1473-1521), who was famed for his sea exploits and even briefly captured Manila; and under the ninth sultan, Hassan (1605-19), who fully developed an elaborate Royal Court structure, elements of which remain today.

After Sultan Hassan, Brunei entered a period of decline, due to internal battles over royal succession as well as the rising influences of European colonial powers in the region, that, among other things, disrupted traditional trading patterns, destroying the economic base of Brunei and many other Southeast Asian sultanates. In 1839, the English adventurer James Brooke arrived in Borneo and helped the Sultan put down a rebellion. As a reward, he became governor and later "Rajah" of Sarawak in northwest Borneo and gradually expanded the territory under his control.

Meanwhile, the British North Borneo Company was expanding its control over territory in northeast Borneo. In 1888, Brunei became a protectorate of the British Government, retaining internal independence but with British control over external affairs. In 1906, Brunei accepted a further measure of British control when executive power was transferred to a British resident, who advised the ruler on all matters except those concerning local custom and religion.

In 1959, a new constitution was written declaring Brunei a self-governing state, while its foreign affairs, security, and defense remained the responsibility of the United Kingdom. An attempt in 1962 to introduce a partially elected legislative body with limited powers was abandoned after the opposition political party, Partai Rakyat Brunei, launched an armed uprising, which the government put down with the help of British forces. In the late 1950s and early 1960s, the government also resisted pressures to join neighboring Sabah and Sarawak in the newly formed Malaysia. The Sultan eventually decided that Brunei would remain an independent state.

In 1967, Sultan Omar abdicated in favor of his eldest son, Hassanal Bolkiah, who became the 29th ruler. The former Sultan remained as Defense Minister and assumed the royal title Seri Begawan. In 1970, the national capital, Brunei Town, was renamed Bandar Seri Begawan in his honor. The Seri Begawan died in 1986.

On January 4, 1979, Brunei and the United Kingdom signed a new treaty of friendship and cooperation. On January 1, 1984, Brunei Darussalam became a fully independent state.