Protectorate Agreement of Brunei (1888)

The Protectorate Agreement of Brunei 1888 or Protectorate Agreement with the Sultan of Brunei or Agreement between Her Majesty's Government and the Sultan of Brunei for the establishment of a British protectorate over the State of Brunei was a treaty signed on 17 September 1888 between the Sultanate of Brunei and the British Empire. The treaty placed Brunei under the protection of the British Government but with certain limitations, however it effectively shifted the entirety of Brunei's foreign affairs to the United Kingdom.

The agreement was signed by the 25th Sultan of Brunei, Sultan Hashim Jalilul Alam Aqamaddin and the British Resident of Perak, Hugh Low. It was witnessed by Dato Temenggong Kim Swee and L.H Wise. It was signed at Sultan Hashim's palace in "the city of Brunei", present day Kampong Ayer.

The treaty marked the end of the Sultanate of Brunei and the beginning of British Protectorate Brunei. It also officially established the British consul system in the Sultanate. The Protectorate system would later develop into a British Residency system after the Report on Brunei. The system would eventually dissolve and be replaced by a Brunei administration in 1959.