Tsetlin was born into a Jewish family in the city of Mogilev in the Russian Empire (modern day Belarus).

[1] From November 1917 to April 1918 he was the Chairman of the District Committee of the Workers' Youth Union in Moscow.

In 1922, Tsetlin became a member of the Executive Committee of the Young Communist International and in the same year, he was sent to Germany for Bolshevik agitation.

From 1929 to 1932, Tsetlin was an employee of the Supreme Soviet of the National Economy and later from 1932 to 1933, he served as the Deputy Head of the Scientific and Research Sector of the People's Commissariat of Heavy Industry.

From 1934 to 1937 he worked as the manager of the Technical Service Office of the Ural Heavy Machinery Factory in Sverdlovsk.