Knorin was born in to a Latvian peasant family and was a member of the Bolshevik Party from 1910.

He served as the second First secretary of the Central Committee of the Communist Party of the Byelorussian SSR from 1920 to 1922 and from 1927 to 1928.

Being a Moscow-appointed de facto head of state of Belarus, Knorin is known for his notorious quote about the Belarusian independence: "We believe that Byelorussians are not a nation, and the ethnographic specifics, which differentiate them from Russians, must be erased.

"[1] From 1926 to 1927 he was head of the propaganda department of the Central Committee of the All-Union Communist Party.

Knorin participated in the preparation of the "History of the Communist Party of the Soviet Union (Bolsheviks)".