At the end of World War II in Europe, Austria was occupied by the Allies and declared independence from Nazi Germany on 27 April 1945 (confirmed by the Berlin Declaration for Germany on 5 June 1945), as a result of the Vienna offensive. The occupation ended when the Austrian State Treaty came into force on 27 July 1955.

After the Anschluss in 1938, Austria had generally been recognized as part of Nazi Germany. In November 1943, however, the Allies agreed in the Declaration of Moscow that Austria would instead be regarded as the first victim of Nazi aggression—without denying Austria's role in Nazi crimes—and treated as a liberated and independent country after the war.

In the immediate aftermath of World War II, Austria was divided into four occupation zones and jointly occupied by the United Kingdom, the Soviet Union, the United States, and France. Vienna was similarly subdivided, but the central district was collectively administered by the Allied Control Council.

While Germany was divided into East and West Germany in 1949, Austria remained under joint occupation of the Western Allies and the Soviet Union until 1955; its status became a controversial subject in the Cold War until the warming of relations known as the Khrushchev Thaw. After Austrian promises of perpetual neutrality, Austria was accorded full independence on 15 May 1955 and the last occupation troops left on 25 October that year.

At the 1943 Moscow Conference, the Soviet Union, United States, and the United Kingdom had jointly decided that the German annexation of Austria would be considered "null and void". In addition, all administrative and legal measures since 1938 would be ignored. The conference declared the intent to create a free and independent Austria after the war, but also stated that Austria had a responsibility for "participation in the war at the side of Hitlerite Germany" which could not be evaded.

On 29 March 1945, Soviet commander Fyodor Tolbukhin's troops crossed the former Austrian border at Klostermarienberg in Burgenland. On 3 April, at the beginning of the Vienna Offensive, the Austrian politician Karl Renner, then living in southern Lower Austria, established contact with the Soviets. Joseph Stalin had already established a would-be future Austrian cabinet from the country's communists in exile, but Tolbukhin's telegram changed Stalin's mind in favor of Renner.

On 20 April 1945, the Soviets, without asking their Western allies, instructed Renner to form a provisional government. Seven days later Renner's cabinet took office, declared the independence of Austria from Nazi Germany, and called for the creation of a democratic state along the lines of the First Austrian Republic. Soviet acceptance of Renner was not an isolated episode; their officers re-established district administrations and appointed local mayors, frequently following the advice of the locals, even before the fighting was over.

Renner and his ministers were guarded and watched by NKVD bodyguards. One-third of State Chancellor Renner's cabinet, including crucial seats of the Secretary of State of the Interior and the Secretary of State for Education, was staffed by Austrian Communists. The Western allies suspected the establishment of a puppet state and refused to recognize Renner. The British were particularly hostile; even American President Harry Truman, who believed that Renner was a trustworthy politician rather than a token front for the Kremlin, denied him recognition. However, Renner had secured inter-party control by designating two Under-Secretaries of State in each of the ministries, appointed by the two parties not designating the Secretary of State.