The Federated Malay States (FMS, Malay: Negeri-Negeri Melayu Bersekutu, Jawi: نݢري٢ ملايو برسکوتو) was a federation of four integrated protectorates in the Malay Peninsula comprising Selangor, Perak, Negeri Sembilan and Pahang. It was established in 1895 by the British government and lasted until 1946. In that year, these states joined with two of the former Straits Settlements (Malacca and Penang, excluding Singapore) and the Unfederated Malay States to form the Malayan Union. The union was short-lived and in 1948 was replaced by the Federation of Malaya, which gained independence in 1957. This federation later became Malaysia in 1963 following the inclusion of North Borneo (now Sabah), Sarawak and Singapore. Singapore was eventually separated from Malaysia and became a sovereign state on 9 August 1965.

Unlike the Unfederated Malay States, which retained greater internal autonomy, the real authority in the FMS resided with the four British Residents and the Resident-General. The powers of the local rulers were significantly restricted and were largely confined to matters "touching Malay religion and customs". The administration of the FMS represented a more centralised and interventionist colonial governance model in contrast to the comparatively decentralised arrangements in the Unfederated States. Nevertheless, the FMS remained nominally more autonomous than the Straits Settlements, which were directly governed by Britain through its Governor.

During World War II, the federation, along with the Unfederated Malay States and the Straits Settlements, was invaded and occupied by Japanese forces which culminated in the Fall of Singapore. After the Japanese surrender and the liberation of Malaya, the original federation was not reinstated. However, the federal model it had introduced remained influential and provided the administrative framework for the Federation of Malaya formed in 1948 and for the eventual creation of Malaysia in 1963.

On 20 January 1874, Sir Andrew Clarke, governor of the Straits Settlements, concluded with the Sultan of Perak the treaty of Pangkor whereby the Sultan agreed to "receive and provide a suitable residence for a British Officer to be called Resident, who shall be accredited to his court, and whose advice must be asked and acted upon on all questions other than those touching Malay Religion and Customs". The residency system was extended the same year to Selangor and Negri Sembilan, and in 1888 to Pahang.

To promote greater administrative efficiency, these four states were brought together in 1895/1896 to form the Federated Malay States. This structure was highly centralized, with real power resting in the hands of the agents of the British Government, at first called the Resident-General, and later the Chief Secretary.

The British established the Federal Council in 1898 to administer the federation. It was headed by the High Commissioner (The Governor of the Straits Settlement), assisted by the Resident-General, the rulers, the four state Residents and four nominated unofficial members. This structure remained until the Japanese invaded Malaya on 8 December 1941.

Although the Resident-General was the real administrator of the federation, each of the four constituent states of the federation retained their respective hereditary rulers. At the formation of the Federated Malay States, the reigning rulers were:

In 1897 the first durbar was convened in the royal town of Kuala Kangsar, Perak as the platform for discussions for the four rulers. This formed the basis for the Conference of Rulers that was created later on under Article 38 of the Malaysian Constitution on 27 August 1957.