Born of an ancient and noble family, Joseph and his elder brother Leon Orbeli were reared in St. Petersburg, where Joseph attended the St. Petersburg University, of which he became a professor in 1914. During his student years he accompanied Nicholas Marr to Armenia where they excavated the ruins of the medieval capital Ani. Gradually, Orbeli emerged as the leading authority on Armenian antiquities in the world. In 1916, he explored the Lake Van region, then conducted important surveys and excavations in Armenia proper. He also studied the local languages (notably Kurdish) and architecture.
This led to his appointment to the Hermitage Museum, which he would steer through the hardships of Stalin's purges and the Siege of Leningrad. Orbeli considerably enhanced the museum's holdings of Oriental art, making it one of the top oriental art museums in the world. No less potent was his role as head of the national school of Caucasus studies. Orbeli underscored the importance of linguistic studies for proper understanding of historical processes. In 1955-60, he was in charge of the Faculty of Oriental Studies at the Leningrad University.