After the February Revolution, in 1917, Oppokov returned to Moscow, and under the name 'Lomov' was elected a candidate member of the Central Committee of the Bolsheviks at the Sixth Party Congress in August 1917. As one of its youngest members, he was a keen backer of Vladimir Lenin's call for a second revolution. On October 3, speaking on behalf of the Moscow Regional Party Committee, while Lenin was in hiding, he delivered a sharp rebuke to fellow members of the Central Committee for wavering on this issue. After the Bolshevik Revolution in November 1917, he was appointed People's Commissar for Justice, but surrendered this post when the Bolsheviks entered into a brief coalition with the Left Socialist Revolutionaries. He was also a Bolshevik candidate in the 1917 Russian Constituent Assembly election, being fielded in the Arkhangelsk constituency. In December he was appointed a member of the Supreme Economic Council (Vesenkha).