Born in Shushi to the family of a tailor, he became a member of the Russian Social Democratic Labour Party in 1902.
In 1918 during the period of the Baku Commune, he was the minister of oil and the chairman of the Emergency Commission.
[1] From 1928 to 1935 he was the Chairman of the Council of People's Commissars of Armenian SSR (equivalent of prime minister).
[1] In 1931, Ter-Gabrielyan openly opposed Joseph Stalin's decision to appoint Lavrentiy Beria second secretary of the Communist Party's regional committee of the Transcaucasian SFSR.
According to the official report presented to Stalin, Ter-Gabrielyan was arrested and purportedly committed suicide by jumping out of a second-floor window.