Democratic Federal Yugoslavia, also known as Democratic Federative Yugoslavia (DF Yugoslavia or DFY), was a provisional state established during World War II on 29 November 1943 through the Second Session of the Anti-Fascist Council for the National Liberation of Yugoslavia (AVNOJ). The National Committee for the Liberation of Yugoslavia (NKOJ) was its original executive body. Throughout its existence it was governed by Marshal Josip Broz Tito as prime minister.

It was recognized by the Allies at the Tehran Conference, along with the AVNOJ as its deliberative body. The Yugoslav government-in-exile of King Peter II in London, partly due to pressure from the United Kingdom, recognized the AVNOJ government with the Treaty of Vis, signed on 16 June 1944 between the prime minister of the government-in-exile, Ivan Šubašić, and Tito. With the Treaty of Vis, the government-in-exile and the NKOJ agreed to merge into a provisional government as soon as possible. The form of the new government was agreed upon in a second Tito–Šubašić agreement signed on 1 November 1944 in the recently liberated Yugoslav capital of Belgrade. DF Yugoslavia became one of the founding members of the United Nations upon the signing of the United Nations Charter in October 1945.

The state was formed to unite the Yugoslav resistance movement to the occupation of Yugoslavia by the Axis powers. The agreement left the issue of whether the state would be a monarchy or a republic intentionally undecided until after the war had ended so the position of head of state was vacant. After the merger of the governments, the state was reformed as a one-party Federal People's Republic of Yugoslavia with Josip Broz Tito as Prime Minister and Ivan Šubašić as minister of foreign affairs.