"Unfederated Malay States" (; Jawi: ) was the collective term for five distinct British protected states situated in the Malay Peninsula during the early to mid-twentieth century. These states were Johor, Kedah, Kelantan, Perlis and Terengganu. In contrast to the neighbouring Federated Malay States comprising Selangor, Perak, Pahang and Negeri Sembilan, the Unfederated Malay States did not share a unified administration or common institutions. Though they were nominally independent, each of them functioned as an individual protectorate under British oversight and were not recognised as a single entity in international law.
Following the conclusion of World War II, the British crown colony known as the Straits Settlements was formally de jure dissolved in 1946 (having been rendered de facto defunct with the Japanese occupation of Malaya and the Fall of Singapore in 1942). These states then became British protected states. With the assistance of Japan, they temporarily returned to Thai jurisdiction for the latter part of World War II but was returned to Britain after the defeat and surrender of the Axis powers.