Dekanozov studied in the medical schools of Saratov University and Baku University. In 1918 he entered the Red Army, and in 1920 he joined the Bolshevik Party. From 1918 he worked as a secret agent in Transcaucasia, first in the People's Commissariat for Health of the short-lived Azerbaijan Democratic Republic, then in private oil companies. After the invasion of Azerbaijan by the Red Army, Dekanozov worked for the Cheka of Azerbaijan SSR, where he befriended Lavrenty Beria, who subsequently supported Dekanozov. In 1921–27 Dekanozov worked for the Cheka in Azerbaijan, Georgia, and Transcaucasia. In 1927 he became an instructor of the Central Committee of the Communist Party of Georgia. In 1928–1931 he worked as one of the leaders of the Georgian and Transcaucasian OGPU. In 1931 he became a secretary of the Central Committee of the Communist Party of Georgia. From 1936 he was the Narkom of the food industry of Georgia, and from 1937 he simultaneously worked as the Chairman of Gosplan of Georgia and a deputy Chairman of Georgian Sovnarkom. He was a deputy of the Supreme Soviet of the USSR in 1937–50.