Rhodesia's Unilateral Declaration of Independence (UDI) was a statement adopted by the Cabinet of Rhodesia on 11 November 1965, announcing that Rhodesia a British territory in southern Africa that had governed itself since 1923, now regarded itself as an independent sovereign state. The culmination of a protracted dispute between the British and Rhodesian governments regarding the terms under which the latter could become fully independent, it was the first unilateral break from the United Kingdom by one of its colonies since the United States Declaration of Independence in 1776. The UK, the Commonwealth, and the United Nations all deemed Rhodesia's UDI illegal, and economic sanctions, the first in the UN's history, were imposed on the breakaway colony. Amid near-complete international isolation, Rhodesia continued as an unrecognised state with the assistance of South Africa and Portugal.

Rhodesia, officially from 1970 the Republic of Rhodesia, was an unrecognised state in Southern Africa from 1965 to 1979, equivalent in territory to modern Zimbabwe. Rhodesia was the de facto successor state to the British colony of Southern Rhodesia, which had been self-governing since achieving responsible government in 1923. A landlocked nation, Rhodesia was bordered by Botswana to the southwest, Mozambique to the east, South Africa to the south, and Zambia to the northwest. From 1965 to 1979, Rhodesia was one of two independent states on the African continent governed by a white minority of European descent and culture, the other being South Africa.