He served as the first professor of social and economic history of the Indian Institute of Management, Calcutta, founder-director of the Centre for Studies in Social Sciences, Calcutta and the Maulana Abul Kalam Azad Institute of Asian Studies, Kolkata and as the honorary state editor for the West Bengal District Gazetteers.
He completed his higher studies at Presidency College, Calcutta, where he was a student of Professor Susobhan Chandra Sarkar.
[5] De, who became a full professor at the age of 33, held various positions at various times, including a senior professorship of social and economic history and programme directorship of the Post-Graduate Training Programme of the Indian Institute of Management, Calcutta,[6] the founder-directorship of the Centre for Studies in Social Sciences, Calcutta and the Maulana Abul Kalam Azad Institute of Asian Studies,[3] a membership, held for three terms, of the Indian Council of Historical Research, New Delhi, a membership of the West Bengal Higher Education Commission and an honorary state editorship of the West Bengal District Gazetteers.
[8] He was appointed as a Tagore National Fellow by the Government of India, which he held at the Victoria Memorial Hall, Calcutta (2011–2013).
In the earlier part of his career he wrote on Henry Dundas and the conquest of India, while later on he addressed the Marxist critique of the colonial context of the Bengal renaissance.
[12] He was also concerned with the national movement: his popular textbook book, Freedom Struggle, co-authored with Bipan Chandra and Amalesh Tripathi,[3] was censored by the new Central government that came to power in India in 1977.
[14] In 1975 he edited a thick volume in honour of Prof. Susobhan Sarkar in which he wrote the main essay on his teacher which reveals his preference for objectivity and critical analysis.
[22] His son, Dr. Bikramjit Dey, is a professor of legal history at the West Bengal National University of Juridical Sciences, Kolkata.