He was born Sergei Mironovich Kostrikov (Ко́стриков), later assuming the name "Kirov" as an alias. Born to a poor family in Urzhum, Russia, Kirov lost his parents when he was young. His father, Miron Kostrikov, had left him at a tender age; his mother Ekaterina Kitun Kostrikov also died in the subsequent year. As a child, Sergei was brought up by his grandmother before being sent to an orphanage at seven years of age. In 1901 a group of wealthy benefactors provided a scholarship for him to attend an industrial school at Kazan. After gaining his degree in Engineering he moved to Tomsk. As Russian society went into crisis, Kirov became a Marxist and joined the Russian Social Democratic Labor Party (RSDLP) in 1904.
By this time, Sergei Kostrikov had changed his name to Kirov. He had selected it as a pseudonym, just as other Russian revolutionary leaders. The name "Kir" reminded him of an ancient Persian leader Cyrus the Great, and he was to become commander of the Bolshevik military administration in Astrakhan. Following the Russian Revolution of 1917, he fought in the Russian Civil War until 1920.
At the 1934 Party Congress where the vote for the new Central Committee was held, Kirov received only three negative votes, the fewest of any candidate, while Stalin received 292 negative votes, the highest of any candidate. Kirov was close friends with Sergo Ordzhonikidze, and together they formed a moderate bloc to Stalin in the Politburo. Later in 1934, Stalin asked Kirov to work for him in Moscow.
On December 1, 1934, Kirov was killed by Leonid Nikolaev in the Smolny Institute Leningrad. Kirov had arrived at the Smolny to work in his office, and, apparently leaving his bodyguard downstairs, headed to the upper floors, where the officials had their rooms. Nikolayev emerged from a bathroom and followed Kirov towards his office, shooting him in the back of the neck.
The investigators from NKVD claimed that Nikolayev was part of a larger conspiracy led by Leon Trotsky against the Soviet government. This resulted in the arrest and execution of Lev Kamenev, Grigory Zinoviev, and fourteen others in 1936. The death of Kirov ignited the great purge where supporters of Trotsky and other suspected enemies of the state were arrested.
Much controversy still exists today over the murder. It has been speculated that it might have been ordered by Stalin, and that the shooting was carried out with the help of the NKVD, but this has never been proven. Others have speculated that Kirov was having an affair with Nikolayev's wife and that though this may not have been the sole factor, the NKVD may have used it to incite him. Again, this has never been proven. Leonid Nikolaev is said to have had a history of mental illness; his attack may have been a random act of violence.
In the city of Kirov a speedskating match , the Priz Imeni S.M. Kirova, was named for him. This match is the longest enduring annual organised race in speedskating apart from the World Speed Skating Championships and the European Speed Skating Championships.
For many years, a huge statue of Kirov in granite and bronze dominated the panorama of the city of Baku. The monument was erected on a hill in 1939 and was dismantled in January 1992, after Azerbaijan gained its independence. The Kirov class of battlecruisers is named in his honor, though the first-of-class vessel originally named Kirov has since been renamed Admiral Ushakov.
In the game Red Alert 2, the Soviets have the ability to build the 'Kirov Airship', an extremely slow but powerful zeppelin.
The assassination of Sergei Kirov is mentioned in the first chapter of Alan Furst's Dark Star as the event that "led to the first round of purges under Yagoda".