Madzimbamuto v Lardner-Burke and another [1969] 1 AC 645 is a decision of the Judicial Committee of the Privy Council on United Kingdom constitutional law and the constitutional law of Rhodesia. The case was brought by Stella Madzimbamuto, to challenge the detention of her husband, Daniel Madzimbamuto, by the government of Rhodesia. The case raised the issue of the legality of the Unilateral Declaration of Independence made by Rhodesia in 1965. The case is often cited in relation to the legal status of constitutional conventions in United Kingdom constitutional law.

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.