Aghayan was born in Meghri and studied at a local primary school before working at a kolkhoz as an accountant.
In 1933 he was admitted to Yerevan State University (YSU), which he graduated in 1938 and completed his post-graduate studies in 1939.
In 1950-53 he served as its vice-director and from 1963 to 1993 he was head of the department of general and comparative linguistics at the institute.
He is best known for his Explanatory Dictionary of Modern Armenian (Արդի հայերենի բացատրական բառարան), published in two volumes in 1976.
[3] His Introduction to Linguistics (Լեզվաբանության ներածություն) was originally published in Armenian in 1952 and was approved by Soviet Ministry of Education as a university textbook and was published in Russian (Введение в языкознание) in 1959.