Born in 1941 in Devon, England, Keay was educated at Ampleforth College, York and Magdalen College, Oxford, where he was a demy (scholar) in Modern History. His tutors included the historian A J P Taylor and the playwright Alan Bennet. He first visited India in 1965 and has been returning there about every two years ever since. After a brief spell as a political correspondent (The Economist), he assisted in the revision of the last edition of John Murray's Handbook to India, Pakistan, Nepal, Bangladesh and Sri Lanka (1975) and wrote Into India, his first book.
A string of acclaimed works followed - and continues. The paperback of his The Honourable Company has been reprinted a dozen times and India: A History went into a new and expanded edition in 2010. The 'exquisitely written' (Observer) China: A History has also become a classic. Midnight's Descendants and The Tartan Turban promise more of the same.
In 2009 the Royal Society for Asian Affairs awarded Keay its Sir Percy Sykes Memorial Medal for his literary contribution to Asian studies, and in 2009 the Royal Literary Fund appointed him to a Literary Fellowship at the University of Dundee and then (2013) at the Royal Conservatoire of Scotland. He has lectured for the British Council all over India and has frequently accompanied tour groups in South and Southeast Asia.
He was married to the author Julia Keay (d 2011) and has four children. He remarried in 2014 to Amanda Douglas; they live partly in Argyll , partly in Edinburgh. John is not attached to any academic faculty and for an income relies mainly on receipts from royalties and rights generated by his books.