Gorbachev attended the important twenty-second Party Congress in October 1961, where Nikita Khrushchev announced a plan to surpass the U.S. in per capita production within twenty years. At this point in his life, Gorbachev would rise in the Communist League hierarchy and worked his way up through territorial leagues of the party. He was promoted to Head of the Department of Party Organs in the Stavropol Agricultural Kraikom in 1963. In 1970, he was appointed First Party Secretary of the Stavropol Kraikom, a body of the CPSU, becoming one of the youngest provincial party chiefs in the nation. In this position he helped reorganise the collective farms, improve workers' living conditions, expand the size of their private plots, and give them a greater voice in planning. He was soon made a member of the Communist Party Central Committee in 1971. Three years later, in 1974, he was made a Representative to the Supreme Soviet of the Soviet Union and Chairman of the Standing Commission on Youth Affairs. He was subsequently appointed to the Central Committee's Secretariat for Agriculture in 1978, replacing Fyodor Kulakov, who had supported Gorbachev's appointment, after Kulakov died of a heart attack. In 1979, Gorbachev was promoted to the Politburo, the highest authority in the country, and received full membership in 1980. Gorbachev owed his steady rise to power to the patronage of Mikhail Suslov, the powerful chief ideologist of the CPSU. During Yuri Andropov's tenure as General Secretary (1982–1984), Gorbachev became one of the Politburo's most visible and active members. With responsibility over personnel, working together with Andropov, 20 percent of the top echelon of government ministers and regional governors were replaced, often with younger men. During this time Grigory Romanov, Nikolai Ryzhkov, and Yegor Ligachev were elevated, the latter two working closely with Gorbachev, Ryzhkov on economics, Ligachev on personnel. In 1972, he headed a Soviet delegation to Belgium, and three years later he led a delegation to West Germany; in 1983 he headed a delegation to Canada to meet with Prime Minister Pierre Trudeau and members of the Commons and Senate. In 1984, he travelled to the United Kingdom, where he met British Prime Minister Margaret Thatcher. Upon Andropov's death in 1984, the aged Konstantin Chernenko took power; after his death the following year, it became clear to the party hierarchy that younger leadership was needed.

Gorbachev was elected General Secretary by the Politburo on 11 March 1985, only three hours after Chernenko's death. Upon his accession at age 54, he was the youngest member of the Politburo. Mikhail Gorbachev was the Party's first leader to have been born after the Revolution. As de facto ruler of the USSR, he tried to reform the stagnating Party and the state economy by introducing glasnost ("openness"), perestroika ("restructuring"), demokratizatsiya ("democratization"), and uskoreniye ("acceleration" of economic development), which were launched at the 27th Congress of the CPSU in February 1986. Gorbachev's primary goal as General Secretary was to revive the Soviet economy after the stagnant Brezhnev years. In 1985, he announced that the Soviet economy was stalled and that reorganization was needed. Gorbachev soon realised that fixing the Soviet economy would be nearly impossible without reforming the political and social structure of the Communist nation. Gorbachev also initiated the concept of gospriyomka ("approval") during his time as leader, which represented state approval of goods in an effort to maintain quality control and combat inferior manufacturing. He made a speech in May 1985 in Leningrad (now St. Petersburg) advocating widespread reforms. The reforms began in personnel changes; the most notable change was the replacement of Andrei Gromyko as Minister of Foreign Affairs with Eduard Shevardnadze. Gromyko, disparaged as "Mr Nyet" in the West, had served for 28 years as Minister of Foreign Affairs and was considered an 'old thinker'.

A number of reformist ideas were discussed by Politburo members. One of the first reforms Gorbachev introduced was the anti-alcohol campaign, begun in May 1985, which was designed to fight widespread alcoholism in the Soviet Union. Domestic changes continued apace. In a bombshell speech during Armenian SSR's Central Committee Plenum of the Communist Party the young First Secretary of Armenia's Hrazdan Regional Communist Party, Hayk Kotanjian, criticised rampant corruption in the Armenian Communist Party's highest echelons, implicating Armenian SSR Communist Party First Secretary Karen Demirchyan and calling for his resignation. Symbolically, intellectual Andrei Sakharov was invited to return to Moscow by Gorbachev in December 1986 after six years of internal exile in Gorky. During the same month, however, signs of the nationalities problem that would haunt the later years of the Soviet Union surfaced as riots, named Jeltoqsan, occurred in Kazakhstan after Dinmukhamed Kunayev was replaced as First Secretary of the Communist Party of Kazakhstan.

The Central Committee Plenum in January 1987 would see the crystallisation of Gorbachev's political reforms, including proposals for multi-candidate elections and the appointment of non-Party members to government positions. He also first raised the idea of expanding co-operatives at the plenum. Economic reforms took up much of the rest of 1987, as a new law giving enterprises more independence was passed in June and Gorbachev released a book, Perestroika: New Thinking for Our Country and the World, in November, elucidating his main ideas for reform. 1988 would see Gorbachev's introduction of glasnost, which gave new freedoms to the people, including greater freedom of speech. At the same time, he opened himself and his reforms up for more public criticism, evident in Nina Andreyeva's critical letter in a March edition of Sovetskaya Rossiya. The Law on Cooperatives enacted in May 1988 was perhaps the most radical of the economic reforms during the early part of the Gorbachev era. For the first time since Vladimir Lenin's New Economic Policy, the law permitted private ownership of businesses in the service, manufacturing, and foreign-trade sectors. In June 1988, at the CPSU's Party Conference, Gorbachev launched radical reforms meant to reduce party control of the government apparatus. He proposed a new executive in the form of a presidential system, as well as a new legislative element, to be called the Congress of People's Deputies. Elections to the Congress of People's Deputies were held throughout the Soviet Union in March and April 1989. This was the first free election in the Soviet Union since 1917. Gorbachev became Chairman of the Supreme Soviet (or head of state) on 25 May 1989. On 15 March 1990, Gorbachev was elected as the first executive President of the Soviet Union with 59% of the Deputies' votes being an unopposed candidate. The Congress met for the first time on 25 May in order to elect representatives from Congress to sit on the Supreme Soviet of the Soviet Union. Boris Yeltsin was elected in Moscow and returned to political prominence to become an increasingly vocal critic of Gorbachev.

In contrast to his controversial domestic reforms, Gorbachev was largely hailed in the West for his 'New Thinking' in foreign affairs. During his tenure, he sought to improve relations and trade with the West by reducing Cold War tensions. He established close relationships with several Western leaders, such as West German Chancellor Helmut Kohl, U.S. President Ronald Reagan, and British Prime Minister Margaret Thatcher. Gorbachev understood the link between achieving international détente and domestic reform and thus began extending 'New Thinking' abroad immediately. On 8 April 1985, he announced the suspension of the deployment of SS-20s in Europe as a move towards resolving intermediate-range nuclear weapons (INF) issues. Later that year, in September, Gorbachev proposed that the Soviets and Americans both cut their nuclear arsenals in half. He went to France on his first trip abroad as Soviet leader in October. November saw the Geneva Summit between Gorbachev and Ronald Reagan. Though no concrete agreement was made, Gorbachev and Reagan struck a personal relationship and decided to hold further meetings. January 1986 would see Gorbachev make his boldest international move so far, when he announced his proposal for the elimination of intermediate-range nuclear weapons in Europe and his strategy for eliminating all nuclear weapons by the year 2000 (often referred to as the 'January Proposal'). He also began the process of withdrawing troops from Afghanistan and Mongolia on 28 July. On 11 October 1986, Gorbachev and Reagan met in Reykjavík, Iceland to discuss reducing intermediate-range nuclear weapons in Europe. To the immense surprise of both men's advisers, the two agreed in principle to removing INF systems from Europe and to equal global limits of 100 INF missile warheads. They also essentially agreed in principle to eliminate all nuclear weapons in 10 years (by 1996), instead of by the year 2000 as in Gorbachev's original outline. In February, 1988, Gorbachev announced the full withdrawal of Soviet forces from Afghanistan. The withdrawal was completed the following year, although the civil war continued as the Mujahedin pushed to overthrow the pro-Soviet Najibullah government. An estimated 28,000 Soviets were killed between 1979 and 1989 as a result of the Afghanistan War. Also during 1988, Gorbachev announced that the Soviet Union would abandon the Brezhnev Doctrine, and allow the Eastern bloc nations to freely determine their own internal affairs. Moscow's abandonment of the Brezhnev Doctrine led to a string of counter-revolutions in Eastern Europe throughout 1989, in which Communism was overthrown. The loosening of Soviet hegemony over Eastern Europe effectively ended the Cold War, and for this, Gorbachev was awarded the Otto Hahn Peace Medal in Gold in 1989 and the Nobel Peace Prize on 15 October 1990.

While Gorbachev's political initiatives were positive for freedom and democracy in the Soviet Union and its Eastern bloc allies, the economic policy of his government gradually brought the country close to disaster. By the end of the 1980s, severe shortages of basic food supplies (meat, sugar) led to the reintroduction of the war-time system of distribution using food cards that limited each citizen to a certain amount of product per month. Compared to 1985, the state deficit grew from 0 to 109 billion rubles; gold funds decreased from 2,000 to 200 tons; and external debt grew from 0 to 120 billion dollars. Furthermore, the democratisation of the Soviet Union and Eastern Europe had irreparably undermined the power of the CPSU and Gorbachev himself. The relaxation of censorship and attempts to create more political openness had the unintended effect of re-awakening long-suppressed nationalist and anti-Russian feelings in the Soviet republics. Calls for greater independence from Moscow's rule grew louder, especially in the Baltic republics of Lithuania, Latvia, and Estonia which had been annexed into the Soviet Union by Stalin in 1940. Nationalist feeling also took hold in Georgia, Ukraine, Armenia and Azerbaijan. In December 1986, the first signs of the nationalities problem that would haunt the later years of the Soviet Union's existence surfaced as riots, named Jeltoqsan, occurred in Alma Ata and other areas of Kazakhstan after Dinmukhamed Kunayev was replaced as First Secretary of the Communist Party of Kazakhstan. Nationalism would then surface in Russia in May 1987, as 600 members of Pamyat, a nascent Russian nationalist group, demonstrated in Moscow and were becoming increasingly linked to Boris Yeltsin, who received their representatives at a meeting. Violence erupted in Nagorno-Karabakh - an Armenian-populated enclave within Azerbaijan - between February and April, when Armenians living in the area began a new wave of protests over the arbitrary transfer of the historically Armenian region from Armenia to Azerbaijan in 1920 upon Joseph Stalin's decision. Turmoil would once again return in late 1988, this time in Armenia itself, when the Leninakan Earthquake hit the region on 7 December. Poor local infrastructure magnified the hazard and some 25,000 people died.

In March and April 1989 elections to the Congress of People's Deputies took place throughout the Soviet Union. This returned many pro-independence republicans, as many CPSU candidates were rejected. The televised Congress debates allowed the dissemination of pro-independence propositions. Indeed, 1989 would see numerous nationalistic expressions protests. Initiated by the Baltic republics in January, laws were passed in most non-Russian republics giving precedence for the republican language over Russian. 9 April would see the crackdown of nationalist demonstrations by Soviet troops in Tbilisi. There would be further bloody protests in Uzbekistan in June, where Uzbeks and Meskhetian Turks clashed in Fergana. Apart from this violence, three major events that altered the face of the nationalities issue occurred in 1989. Estonia had declared its sovereignty in November, 1988, to be followed by Lithuania in May 1989 and by Latvia in July (the Communist Party of Lithuania would also declare its independence from the CPSU in December). This brought the Union and the republics into clear confrontation and would form a precedent for other republics. Finally, the Eastern bloc collapsed in the autumn of 1989, raising hopes that Gorbachev would extend his non-interventionist doctrine to the internal workings of the USSR. 1990 began with nationalist turmoil in January. Azerbaijanis rioted and troops were sent in to restore order; many Moldavians demonstrated in favour of unification with the post-Communist Romania; and Lithuanian demonstrations continued. The same month, in a hugely significant move, Armenia asserted its right to veto laws coming from the All-Union level, thus intensifying the 'war of laws' between republics and Moscow.

Soon after, the CPSU, which had already lost much of its control, began to lose even more power as Gorbachev deepened political reform. The February Central Committee Plenum advocated multi-party elections; local elections held between February and March returned a large number of pro-independence candidates. The Congress of People's Deputies then amended the Soviet Constitution in March, removing Article 6, which guaranteed the monopoly of the CPSU. The process of political reform was therefore coming from above and below, and was gaining a momentum that would augment republican nationalism. Soon after the constitutional amendment, Lithuania declared independence and elected Vytautas Landsbergis as President. On 15 March, Gorbachev himself was elected as the only President of the Soviet Union by the Congress of People's Deputies and chose a Presidential Council of 15 politicians. Gorbachev was essentially creating his own political support base independent of CPSU conservatives and radical reformers. The new Executive was designed to be a powerful position to guide the spiraling reform process, and the Supreme Soviet of the Soviet Union and Congress of People's Deputies had already given Gorbachev increasingly presidential powers in February. This would be again a source of criticism from reformers. Boris Yeltsin was reaching a new level of prominence, as he was elected Chairman of the Presidium of the Supreme Soviet of the Russian SFSR in May, effectively making him the de jure leader of the Russian Soviet Federative Socialist Republic. Problems for Gorbachev would once more come from the Russian parliament in June, when it declared the precedence of Russian laws over All-Union level legislation.

Gorbachev's personal position continued changing. At XXVIIIth CPSU Congress in July, Gorbachev was re-elected General Secretary but this position was now completely independent of Soviet government, and the Politburo had no say in the ruling of the country. Gorbachev further reduced Party power in the same month, when he issued a decree abolishing Party control of all areas of the media and broadcasting. At the same time, Gorbachev was working to consolidate his Presidential position, culminating in the Supreme Soviet granting him special powers to rule by decree in September in order to pass a much-needed plan for transition to a market economy. However, the Supreme Soviet could not agree on which programme to adopt. Gorbachev pressed on with political reform, his proposal for setting up a new Soviet government, with a Soviet of the Federation consisting of representatives from all 15 republics, was passed through the Supreme Soviet in November. In December, Gorbachev was once more granted increased executive power by the Supreme Soviet, arguing that such moves were necessary to counter "the dark forces of nationalism". Such moves led to Eduard Shevardnadze's resignation; Gorbachev's former ally warned of an impending dictatorship. This move was a serious blow to Gorbachev personally and to his efforts for reform. Meanwhile, Gorbachev was losing further ground to nationalists. October 1990 saw the founding of DemoRossiya, the Russian nationalist party; a few days later, both Ukraine and Russia declared their laws completely sovereign over Soviet level laws. The 'war of laws' had become an open battle, with the Supreme Soviet refusing to recognise the actions of the two republics. Gorbachev would publish the draft of a new union treaty in November, which envisioned a continued union called the Union of Sovereign Soviet Republics, but, going into 1991, the actions of Gorbachev were steadily being overtaken by the centrifugal secessionist forces.

January and February would see a new level of turmoil in the Baltic republics. On 10 January 1991 Gorbachev issued an ultimatum-like request addressing the Lithuanian Supreme Council demanding the restoration of the validity of the constitution of the Soviet Union in Lithuania and the revoking of all anti-constitutional laws. As a result of continued violence, at least 14 civilians were killed and more than 600 injured from 11-13 January 1991 in Vilnius, Lithuania. The strong Western reaction and the actions of Russian democratic forces put the president and government of the Soviet Union into an awkward situation, as news of support for Lithuanians from Western democracies started to appear. Further problems surfaced in Riga, Latvia, on 20 January and 21, where OMON (special Ministry of the Interior) troops killed 4 people. Archie Brown suggests that Gorbachev's response this time was better, condemning the rogue action, sending his condolences and suggesting that secession could take place if it went through the procedures outlined in the Soviet constitution. Gorbachev thus continued to draw up a new treaty of union which would have created a truly voluntary federation in an increasingly democratised Soviet Union. The new treaty was strongly supported by the Central Asian republics, who needed the economic power and markets of the Soviet Union to prosper. However, the more radical reformists, such as Russian SFSR President Boris Yeltsin, were increasingly convinced that a rapid transition to a market economy was required and were more than happy to contemplate the disintegration of the Soviet Union if that was required to achieve their aims. On 12 June 1991 Boris Yeltsin was elected President of the Russian Federation by 57.3% of the vote (with a turnout of 74%).

Hardliners in the Soviet leadership, calling themselves the 'State Emergency Committee', launched the August coup in 1991 in an attempt to remove Gorbachev from power and prevent the signing of the new union treaty. During this time, Gorbachev spent three days (19, 20 and 21 August) under house arrest at a dacha in the Crimea before being freed and restored to power. However, upon his return, Gorbachev found that neither union nor Russian power structures heeded his commands as support had swung over to Yeltsin, whose defiance had led to the coup's collapse.

Between 21 August and 22 September, Estonia, Latvia, Lithuania, Ukraine, Belarus, Moldova, Georgia, Armenia, Azerbaijan, Kazakhstan, Kyrgyzstan, Uzbekistan, Tajikistan, and Turkmenistan declared their intention to leave the Soviet Union. Simultaneously, Boris Yeltsin ordered the CPSU to suspend its activities on the territory of Russia and closed the Central Committee building at Staraya Ploschad. The Russian flag now flew beside the Soviet flag at the Kremlin. In light of these circumstances, Gorbachev resigned as General Secretary of the CPSU on 24 August and advised the Central Committee to dissolve. Gorbachev's hopes of a new Union were further hit when the Congress of People's Deputies dissolved itself on 5 September. Though Gorbachev and the representatives of 8 republics (excluding Azerbaijan, Georgia, Moldova, Ukraine, Lithuania, Latvia and Estonia) signed an agreement on forming a new economic community on 18 October, events were overtaking Gorbachev. With the country in a rapid state of deterioration, the final blow to Gorbachev's vision was effectively dealt by a Ukrainian referendum on 1 December, where the Ukrainian people voted for independence. The presidents of Russia, Ukraine and Belarus met in Belovezh Forest, near Brest, Belarus, on 8 December, founding the Commonwealth of Independent States and declaring the end of the Soviet Union in the Belavezha Accords. Gorbachev was presented with a fait accompli and reluctantly agreed with Yeltsin, on 17 December, to dissolve the Soviet Union. Gorbachev resigned on 25 December and the Soviet Union was formally dissolved the next day.The Soviet Union was offically dissolved the following day on December 26, 1991. Two days after Gorbachev left office, on 27 December, Yeltsin moved into Gorbachev's old office.

Following his resignation and the collapse of the Soviet Union, Gorbachev remained active in Russian politics. Especially during the early years of the post-Soviet era, he expressed criticism at the reforms carried out by Russian president Boris Yeltsin. When president Yeltsin called a referendum for 25 April 1993 in an attempt to achieve even greater powers as president, Gorbachev did not vote, and instead called for new presidential elections to happen soon.

Following a failed run for the presidency in 1996, Gorbachev established the Social Democratic Party of Russia, a union between several Russian social democratic parties. He resigned as party leader in May 2004 over a disagreement with the party's chairman over the direction taken in the December 2003 election campaign. The party was later banned in 2007 by the Supreme Court of the Russian Federation due to its failure to establish local offices with at least 500 members in the majority of Russian regions, which is required by Russian law for a political organisation to be listed as party. Later that year, Gorbachev founded a new political party, called the Union of Social-Democrats. In June 2004, Gorbachev represented Russia at the funeral of Ronald Reagan.

Since his resignation, Gorbachev has remained involved in world affairs. He founded the Gorbachev Foundation in 1992, headquartered in San Francisco, California. He later founded Green Cross International, with which he was one of three major sponsors of the Earth Charter. He also became a member of the Club of Rome and the Club of Madrid. In the decade that followed the Cold War, Gorbachev opposed both the U.S.-led NATO bombing of Yugoslavia in 1999 and the U.S.-led Iraq War in 2003. Concerning the 2008 South Ossetia war, in a 12 August 2008 op-ed in The Washington Post, Gorbachev criticized the U.S. support for Georgian President Mikhail Saakashvili and for moving to bring Caucasus into the sphere of its "national interest." In September 2008 Gorbachev announced he would make a comeback to the Russian politics along with a former KGB officer,Alexander Lebedev. Their party is known as the Independent Democratic Party of Russia. He also is part owner of the opposition newspaper Novaya Gazeta. To commemorate the 20th anniversary of the fall of the Berlin Wall, Gorbachev accompanied former Polish leader Lech Walesa and German Chancellor Angela Merkel at a celebration in Berlinon 9 November 2009.

Gorbachev calls for a kind of perestroika or restructuring of societies around the world, starting in particular with that of the United States, because he is of the view that the economic crisis of 2007-present shows that the Washington consensus economic model is a failure that will sooner or later have to be replaced. According to Gorbachev, countries such as Brazil, Malaysia and China which rejected the Washington consensus and the International Monetary Fund approach to economic development, have done far better economically on the whole and achieved far more fair results for the average citizen, than countries that accepted it.