Adontz was born Nikoghayos Ter-Avetikian (Armenian: Նիկողայոս Տեր-Ավետիքյան) in the village of Brnakot in Sisian, which was then part of the Zangezur uezd of the Elizavetpol Governorate (present-day Syunik).

[1] Adontz was accepted to the University of St. Petersburg and studied at the Departments of Oriental Languages and History and Philology under the general direction of the renowned historian and linguist Nicholas Marr.

[2] Adontz left more than 80 monographs on the history and literature of Medieval Armenia, Armenian-Byzantine relations, Armenian-Greek philology, mythology, religion, linguistics in the Armenian, Russian and French languages.

His Armenia in the Period of Justinian (in Russian, Armeniia v epokhu Iustiniana: Politicheskoe sostoianie na osnove Nakhararskogo stroia), based on his dissertation, however, is considered to be the most notable and one of the "most important achievements in Armenian studies of the 20th century.

Adontz also condemned Soviet Russia for signing the 1918 Treaty of Brest Litovsk, which effectively left the once-Armenian-populated regions within the borders of the Ottoman Empire.