In 1921 Kojoyan went to Tabriz, where the artist studied the culture of the ancient eastern country of Persia, and began to take an active part in the cultural life of the local Armenian community. Kojoyan gave lectures at the Art Studio organized by Alexander Tamanian. In 1922 he returned to the Armenian SSR.
During those years the cultural life in Yerevan was flourishing, the School of Fine Arts was founded by the Society of Fine Arts Workers of Armenia with its departments of painting, sculpture and applied arts. Artists were involved in the works of the Haypethrat, the State Theater and the press. In 1939 Kojoyan participated in a ten-day exhibition of Armenian art in Moscow and was awarded the Order of the Red Banner of Labour, meanwhile he received the title of People's Artist of the Republic.