Yezhov was born in Saint Petersburg and from 1915 to 1917, Yezhov served in the Tsarist Russian army. He joined the Bolsheviks on May 5, 1917, in Vitebsk, a few months before the October Revolution. During the Russian Civil War 1919–1921 he fought in the Red Army.
After February 1922, he worked in the political system, rising in 1934
to the Central Committee of the Communist Party; in the next year he
became a secretary of the Central Committee. From February 1935 to March
1939 he was also the Chairman of the Central Commission for Party
Control.
In 1935 he wrote a paper in which he argued that political opposition
must eventually lead to violence and terrorism; this became in part the
ideological basis of the Purges. He became People's Commissar for Internal Affairs (head of the NKVD) and a member of the Presidium Central Executive Committee
on September 26, 1936. Under Yezhov, the purges reached their height,
with roughly half of the Soviet political and military establishment
being imprisoned or shot, along with hundreds of thousands of others,
suspected of disloyalty or "wrecking." Yezhov himself fell out of Stalin's favour and on April 10, 1939, he was arrested. On February 4, 1940, he was executed.