The Hungarian People's Republic (Hungarian: Magyar Népköztársaság) was a one-party socialist state from 20 August 1949 to 23 October 1989. It was governed by the Hungarian Socialist Workers' Party, which was under the influence of the Soviet Union. Pursuant to the 1944 Moscow Conference, Winston Churchill and Joseph Stalin had agreed that after the war Hungary was to be included in the Soviet sphere of influence. The HPR remained in existence until 1989, when opposition forces brought the end of communism in Hungary.

The state considered itself the heir to the Republic of Councils in Hungary, which was formed in 1919 as the first communist state created after the Russian Soviet Federative Socialist Republic (Russian SFSR). It was designated a "people's democratic republic" by the Soviet Union in the 1940s. Geographically, it bordered Romania and the Soviet Union (via the Ukrainian SSR) to the east; Yugoslavia (via SRs Croatia, Serbia, and Slovenia) to the southwest; Czechoslovakia to the north and Austria to the west.

The Communists spent the next year and a half after the Moscow Conference consolidating their hold on power and emasculating the other parties. This culminated in October 1947, when the Communists told their non-Communist coalition partners that they had to cooperate with a reconfigured coalition government if they wanted to stay in the country. The process was more or less completed in 1949, when a newly elected legislature chosen from a single Communist-dominated list adopted a Soviet-style constitution, and the country was officially recast as a "people's republic."

The same political dynamics continued through the years, with the Soviet Union pressing and maneuvering Hungarian politics through the Hungarian Communist Party, intervening whenever it needed to, through military coercion and covert operations. Political repression and economic decline led to a nationwide popular uprising in October–November 1956 known as the Hungarian Revolution of 1956, which was the largest single act of dissent in the history of the Eastern Bloc. After initially allowing the Revolution to run its course, the Soviet Union sent thousands of troops and tanks to crush the opposition and install a new Soviet-controlled government under János Kádár, killing thousands of Hungarians and driving hundreds of thousands into exile. But by the early 1960s, the Kádár government had considerably relaxed its line, implementing a unique form of semi-liberal Communism known as "Goulash Communism". The state allowed imports of certain Western consumer and cultural products, gave Hungarians greater freedom to travel abroad, and significantly rolled back the secret police state. These measures earned Hungary the moniker of the "merriest barrack in the socialist camp" during the 1960s and 1970s.

One of the longest-serving leaders of the 20th century, Kádár would finally retire in 1988 after being forced from office by even more pro-reform forces amidst an economic downturn. Hungary stayed that way until the late 1980s, when turmoil broke out across the Eastern Bloc, culminating with the fall of the Berlin Wall and the Soviet Union's dissolution. Despite the end of communist control in Hungary, the 1949 constitution remained in effect with amendments to reflect the country's transition to liberal democracy. On 1 January 2012, the 1949 constitution was replaced with the brand new constitution.