Following his family's relocation to Kotelnich in the Vyatka province, he began his career in the regional consumer union before transitioning to Komsomol work.

Sokolov was appointed Minister of Defense of the Soviet Union in 1984 and held this post until 1987, when he was dismissed by Mikhail Gorbachev as a result of the Mathias Rust affair.

For some time he was an adviser to the Commander-in-Chief of the United Armed Forces of the Commonwealth of Independent States/ From 1992, Sokolov was an advisor to the Minister of Defense of the Russian Federation.

He was buried on 3 September with full military honors at the Novodevichy Cemetery in Moscow, next to his wife of 70 years, Maria Samojlovna Sokolova (16 December 1919 – 28 August 2012) who had predeceased him three days prior.

[3] He was survived by two sons, Colonel-General Valery Sergeyevich (born 30 September 1940), now a lecturer at the Faculty of Command and General Staff Military Academy, and Colonel-General Vladimir Sergeyevich (born 22 January 1947), who had retired during the war in Afghanistan and was chief of staff of the 40th Army.