South Maluku, also South Moluccas, officially the Republic of South Maluku, is an unrecognized secessionist republic that claims the islands of Ambon, Buru, and Seram, which make up the Indonesian province of Maluku.

Dutch conquest exerted colonial control across the archipelago in the 19th century, establishing a unitary administration. The borders of present-day Indonesia were formed through colonial expansion finalised in the 20th century. After the occupation by the Japanese Empire during World War II ended in 1945, nationalist leaders on Java unilaterally declared Indonesian independence. Early organised indigenous resistance came from the South Moluccas with support and aid from the Dutch government and military. The South Moluccan rebels initially clung on to an early post-colonial treaty prescribing a federal form of statehood. When that treaty, agreed between the Dutch government and the Indonesian government in December 1949, was broken, they unilaterally declared a fully independent Republic of South Maluku (RMS) in April 1950. The South Moluccan leaders based their decision on the treaty, which stipulated autonomy for each of the states of the federation.

After the defeat of the RMS on Ambon by Indonesian forces in November 1950, the self-declared government withdrew to Seram, where an armed struggle continued on until December 1963. The government in exile moved to the Netherlands in 1966, following resistance leader and president Chris Soumokil's capture and execution by Indonesian authorities. The exiled government continues to exist, with John Wattilete as its incumbent president since April 2010. The Republic of South Maluku has been a member state of the Unrepresented Nations and Peoples Organization (UNPO) since 1991.