The Malayan Union was a federation of the Malay states and the Straits Settlements of Penang and Malacca. It was the successor to British Malaya and was conceived to unify the Malay Peninsula under a single government so as to simplify administration. The Malayan Union later became the independent Federation of Malaya in 1948. The Federation of Malaya became the Federation of Malaysia in 1963, following the admission of Singapore, Sabah (North Borneo) and Sarawak to the new federation. Singapore left the federation and became independent in 1965.

On April 1, 1946, the Malayan Union officially came into existence with Sir Edward Gent as its governor. The capital of the Union was Kuala Lumpur.

The idea of the Union was first expressed by the British on October 1945 (plans had been presented to the War Cabinet as early as May 1944) in the aftermath of the Second World War by the British Military Administration. Sir Harold MacMichael was assigned the task of gathering the Malay state rulers' approval for the Malayan Union in the same month. In a short period of time, he managed to obtain all the Malay rulers’ approval. The reasons for their agreement, despite the loss of political power that it entailed for the Malay rulers, has been much debated; the consensus appears to be that the main reasons were that as the Malay rulers were of course resident during the Japanese occupation, they were open to the accusation of collaboration, and that they were threatened with dethronement. Hence the approval was given, though it was with utmost reluctance.