The French Fourth Republic (French: Quatrième république française) was the republican government of France from 27 October 1946 to 4 October 1958, governed by the fourth republican constitution. It was in many ways a revival of the Third Republic that was in place from 1870 during the Franco-Prussian War to 1940 during World War II, and suffered many of the same problems. France adopted the constitution of the Fourth Republic on 13 October 1946.

Despite the political dysfunction, the Fourth Republic saw an era of great economic growth in France and the rebuilding of the nation's social institutions and industry after World War II, with assistance from the United States provided through the Marshall Plan. It also saw the beginning of the rapprochement with former longtime enemy Germany, which in turn led to Franco-German co-operation and eventually to the development of the European Union.

Some attempts were also made to strengthen the executive branch of government to prevent the unstable situation that had existed before the war, but the instability remained and the Fourth Republic saw frequent changes in government – there were 21 administrations in its 12-year history. Moreover, the government proved unable to make effective decisions regarding decolonization of the numerous remaining French colonies. After a series of crises, most importantly the Algerian crisis of 1958, the Fourth Republic collapsed. Wartime leader Charles de Gaulle returned from retirement to preside over a transitional administration that was empowered to design a new French constitution. The Fourth Republic was dissolved on 5 October 1958 following a public referendum which established the modern-day Fifth Republic with a strengthened presidency.