Which island is divided among Indonesia, Malaysia, and Brunei? Borneo. The island is politically shared by Indonesia, Malaysia, and the sovereign state of Brunei.
Indonesia administers roughly the southern three-quarters of Borneo, a region commonly called Kalimantan. Malaysia controls the northern states of Sabah and Sarawak, while Brunei occupies two small coastal enclaves on the northwestern shore. The borders largely reflect former Dutch and British colonial divisions.
Borneo is the third-largest island in the world and contains some of the planet's oldest tropical rainforests. Its wildlife includes orangutans, proboscis monkeys, Bornean pygmy elephants, and the rare clouded leopard. Hundreds of Indigenous communities, often collectively described as Dayak, have long lived across its interior and uplands.
The island is sometimes confused with New Guinea, which is also divided among several political entities. Borneo's three-way division is distinctive because one of its territories is a fully independent country, Brunei, while the others are parts of Indonesia and Malaysia.