Sukhomlin was born in a village in the Chernigov Governorate, Russian Empire (now Chernihiv Oblast, Ukraine). He graduated from an industrial school in Irkutsk in 1917 and worked as a locksmith for the local Trans-Baikal Railway station. In 1918 he joined the Red Guards as a machine gunner and helped suppress the Revolt of the Czechoslovak Legion and served on several Soviet steamships on Lake Baikal. He was transferred to the Amur Front after the Empire of Japan and the White movement captured Khabarovsk, located on the Amur River. He later completed the Vystrel course and graduated from the M. V. Frunze Military Academy. He served as head of the faculty's training department at Frunze Military Academy and then as commissioner for the academy's preparatory course from 1931 to 1933. In 1936 he was appointed an assistant army inspector for the Special Red Banner Far Eastern Army. In 1937 he became the course director at the Soviet General Staff Academy after graduating from that institution in October 1936. In February 1941 he was named an assistant professor.