Brunei is almost completely surrounded by the state of Sarawak Malaysia on the island of Borneo.
Brunei . Apart from its coastline with the South China Sea , the country is completely surrounded by the state of Sarawak , Malaysia . Brunei is the only sovereign state completely on the island of Borneo ; the remainder of the island 's territory is divided between the nations of Malaysia and Indonesia . Sarawak . Located in northwest Borneo , Sarawak is bordered by the state of Sabah to the northeast , Kalimantan , the Indonesian portion of Borneo , to the south , and the independent state of Brunei in the north .