He was born on November 12, 1938, in Leiah, West Punjab (now in Pakistan).He did his schooling in Ambala and then studied at Kirori Mal College, Delhi University. He served as a historian at the National Council of Education Research and Training (NCERT).
Arjun Dev served as Member Secretary of the National Steering Committee on Textbook evaluation. One of his books, which was discontinued by NCERT and was republished by Orient Blackswan as “History of the World: From the Late 19th to the Early 20th century”, has remained a widely read text.

After retiring from the NCERT, Prof. Arjun took up another major enterprise, the Towards Freedom Project of the Indian Council of Historical Research. It was a project conceived as a rejoinder to the British government-inspired Transfer of Power Volumes which documented the history of the last ten years of colonial rule in India in a manner that did scant justice to our great national liberation struggle.