Born in Nizhny Novgorod to a Jewish family active in revolutionary politics, Sverdlov joined the Russian Social Democratic Labour Party in 1902 and supported Vladimir Lenin's Bolshevik faction from 1903.

He played major roles in the dissolution of the Constituent Assembly in January 1918, in persuading party members to support the Treaty of Brest-Litovsk signed with the Central Powers that March, and in authorising the execution of the Romanov family that July.

After his wife's death in 1900, Mikhail converted with his family to the Russian Orthodox Church, married Maria Aleksandrovna Kormiltseva, and had two more sons, Herman and Alexander.

Mikhail watched as his household slowly became a revolutionary hotspot, where the Novgorod Social Democrats would meet, write pamphlets, and even forge stamps for false passports.

[4]: 147 Yakov excelled at school, and after 4 years in gymnasium left to become a pharmacist's apprentice and a "professional revolutionary," Sverdlov joined while a teenager the Russian Social Democratic Labour Party in 1902, and then later the Bolshevik faction, supporting Vladimir Lenin.

After the 1917 February Revolution Sverdlov returned to Petrograd from exile as head of the Urals Delegation and found his way into Lenin's inner circle.

He first met Lenin in April 1917, and was elected as one of five members of the Central Committee's Secretariat in August 1917, after which he usurped Elena Stasova as the body's leading figure.

According to Podvoisky, the chairperson of the Military Revolutionary Committee, "The person who did more than anyone to help Lenin with the practicalities of translating convictions into votes was Sverdlov.

"[4][page needed] As chairman of the Central Committee, Yakov played an important role in planning the October Revolution and helped make the decision to stage an armed uprising.

When the results came back showing that the Socialist Revolutionaries had won, Sverdlov, Lenin, and Bukharin dissolved the assembly, leading to a civil war.

He promoted his friend and suite-mate Varlam Avanesov to second-in-command at the Central Executive Committee, and would later become a top official of the secret police.

[4]: 134  Sverdlov was elected chairman of the All-Russian Central Executive Committee in November 1917, of which his wife was also a part, becoming therefore de jure head of state of the Russian SFSR until his death.

He played important roles in the decision in January 1918 to end the Russian Constituent Assembly and the subsequent signing on 3 March of the Treaty of Brest-Litovsk.

[4]: 147 In March 1918, Sverdlov and the Central Executive Committee discussed how to best remove the "ulcers that socialism has inherited from capitalism" and Yakov advocated for a concentrated effort to turn the poorest peasants in the villages against their kulak brethren.

Alongside Bukharin, the party began a campaign of "concentrated violence" against many members of the landowning, capitalist, and tradesman classes of Russian society.

[4][page needed] A number of sources claim that Sverdlov, alongside Lenin and Goloshchyokin, played a major role in the execution of Tsar Nicholas II and his family on 17 July 1918.

[7][8][9][10][11] However Yuri Slezkine in his book The Jewish Century expressed a slightly different opinion: "Early in the Civil War, in June 1918, Lenin ordered the killing of Nicholas II and his family.

[14] According to Leon Trotsky's diaries, after returning from the front (of the Russian Civil War) he had the following dialogue with Sverdlov:[15] My next visit to Moscow took place after the [temporary] fall of Ekaterinburg [to anti-Communist forces].

"[4]: 158  Under his and Lenin's leadership, the Central Executive Committee adopted Sverdlov's resolution calling for "mass red terror against the bourgeoisie and its agents.

"[4]: 159 Sverdlov supported the Red Terror campaign, specifically when it came to the policy of decossackization that was started in 1917 as a part of the Russian Civil War.

Sverdlov wrote that "not a single crime against the revolutionary military spirit will remain unpunished," and that the release of Cossack prisoners was unacceptable.

[4]: 163  This policy was temporarily suspended in March 1919 while Sverdlov was in Ukraine overseeing the election of the Ukrainian Communist Party's central committee.

Anatoly Lunacharsky, the People's Commissar for Education, wrote that Sverdlov (not Stalin) was the effective leader of the Bolshevik party during the July disturbances in 1917, when Lenin was in hiding and Trotsky and others were under arrest.

Sverdlov was married to a meteorologist, Klavdia Novgorodtseva (1876–1960), who had joined the Bolsheviks in Yekaterinburg, her home town, in 1904, and was arrested for organising an illegal printing press.

[21] In 1915 Klavdia joined Yakov in exile in the village of Monastyrskoe, where together they ran a Bolshevik reading circle in the town, which, though illegal, escaped the notice of the local authorities.