Pastoureau was born in Paris on 17 June 1947. He studied at the École Nationale des Chartes, a college for prospective archivists and librarians. After writing his 1972 thesis about heraldic bestiaries in the Middle Ages, he worked in the coins, medals and antiquities department of the French National Library until 1982.
Since 1983 he has held the Chair of History of Western Symbolism (Chaire d'histoire de la symbolique occidentale) and is a director of studies at the Sorbonne's École pratique des hautes études. He is an academician of the Académie internationale d'héraldique (International Academy of Heraldry) and vice-president of the Société française d'héraldique (French Heraldry Society). When he received an honorary doctorate from the University of Lausanne in 1996, he was described as an eminent scholar who has made a radical contribution to several disciplines.
Professor Pastoureau has published widely, including work on the history of colours, animals, symbols, and the Knights of the Round Table. He has also written on emblems and heraldry, as well as sigillography and numismatics.