The Russian Soviet Federative Socialist Republic (Russian SFSR or RSFSR), previously known as the Russian Socialist Federative Soviet Republic and the Russian Soviet Republic, and unofficially as Soviet Russia, was a socialist state from 1917 to 1922, and afterwards the largest and most populous constituent republic of the Soviet Union (USSR) from 1922 to 1991, until becoming a sovereign part of the Soviet Union with priority of Russian laws over Union-level legislation in 1990 and 1991, the last two years of the existence of the USSR. The Russian SFSR was composed of sixteen smaller constituent units of autonomous republics, five autonomous oblasts, ten autonomous okrugs, six krais and forty oblasts. Russians formed the largest ethnic group. The capital of the Russian SFSR and the USSR as a whole was Moscow and the other major urban centers included Leningrad (Petrograd until 1924), Stalingrad (Volgograd after 1961), Novosibirsk, Sverdlovsk, Gorky and Kuybyshev.

On 7 November 1917 [O.S. 25 October], as a result of the October Revolution, the Russian Soviet Republic was proclaimed as a sovereign state and the world's first constitutionally socialist state guided by communist ideology. The first constitution was adopted in 1918. In 1922, the Russian SFSR signed a treaty officially creating the USSR. On 12 June 1990, the Congress of People's Deputies adopted the Declaration of State Sovereignty. On 12 June 1991, Boris Yeltsin, supported by the Democratic Russia pro-reform movement, was elected the first and only President of the RSFSR, a post that would later become the Presidency of the Russian Federation. The August 1991 Soviet coup d'état attempt in Moscow with the temporary brief internment of President Mikhail Gorbachev destabilised the Soviet Union. Following these events, Gorbachev lost all his remaining power, with Yeltsin superseding him as the pre-eminent figure in the country. On 8 December 1991, the heads of Russia, Ukraine and Belarus signed the Belovezha Accords declaring dissolution of the USSR and established the Commonwealth of Independent States (CIS) as a loose replacement confederation. On 12 December, the agreement was ratified by the Supreme Soviet (the parliament of the Russian SFSR); therefore the Russian SFSR had renounced the Treaty on the Creation of the USSR and de facto declared Russia's independence from the USSR itself and the ties with the other Soviet republics.

On 25 December 1991, following the resignation of Gorbachev as President of the Soviet Union, the Russian SFSR was renamed the Russian Federation. The next day, the USSR was self-dissolved by the Soviet of the Republics on 26 December, which by that time was the only functioning parliamentary chamber of the All-Union Supreme Soviet. After the dissolution, Russia took full responsibility for all the rights and obligations of the USSR under the Charter of the United Nations, including the financial obligations. As such, Russia assumed the Soviet Union's UN membership and permanent membership on the Security Council, nuclear stockpile and the control over the armed forces; Soviet embassies abroad became Russian embassies.

The 1978 constitution of the Russian SFSR was amended several times to reflect the transition to democracy, private property and market economy. The new Russian constitution, coming into effect on 25 December 1993 after a constitutional crisis, completely abolished the Soviet form of government and replaced it with a semi-presidential system. The economy of Russia became heavily industrialized, accounting for about two-thirds of the electricity produced in the USSR. By 1961, it was the third largest producer of petroleum due to new discoveries in the Volga-Urals region and Siberia. In 1974, there were 475 institutes of higher education in the republic providing education in 47 languages to some 23,941,000 students. A network of territorially organized public-health services provided health care. The economy began to be liberalized starting in 1985 under Gorbachev's "perestroika" restructuring policies, including the introduction of non-state owned enterprises (e.g. cooperatives).

Under the leadership of Vladimir Lenin (1870–1924) and Leon Trotsky (1879–1940), the Bolsheviks established the Soviet state on 7 November [O.S. 25 October] 1917. This happened immediately after the October Revolution toppled the interim Russian Provisional Government (most recently led by opposing democratic socialist Alexander Kerensky (1881–1970)) which had governed the new Russian Republic after the abdication of the Russian Empire government of the Romanov imperial dynasty of Tsar Nicholas II the previous March (Old Style: February). The October Revolution was thus the second of the two Russian Revolutions of the turbulent year of 1917. Initially, the new Soviet state did not have an official name and was not recognized by neighboring countries for five months.

Anti-Bolsheviks soon suggested new names, however. By 1919 they had coined the mocking label Sovdepia (Russian: Совдепия) for the nascent state of the Soviets of Workers' and Peasants' Deputies. Speakers of colloquial English coined the term "Bololand" to refer to the land of the Bolos (a term identified from 1919 onwards with the Bolsheviks).

On 25 January 1918 the third meeting of the All-Russian Congress of Soviets proclaimed the establishment of the Russian Soviet Republic. In July 1918, the Fifth All–Russian Congress of Soviets adopted both the new name, Russian Socialist Federative Soviet Republic (RSFSR), and the Constitution of the Russian SFSR.^{[better source needed]}

Internationally, the Russian SFSR was recognized as an independent state in 1920 only by its bordering neighbors (Estonia, Finland, Latvia and Lithuania) in the Treaty of Tartu and by the short-lived Irish Republic of 1919–1922 in Ireland.