He was born at Wells, Somerset, the son of Prebendary William Keate, D.D., rector of Laverton, Somerset, and brother of Robert Keate FRCS (1777-1857), Serjeant-Surgeon to King William IV and Queen Victoria.
He was educated at Eton and King's College, Cambridge. Taking holy orders, he became, about 1797, an assistant master at Eton College. In 1809 he was elected headmaster. The discipline of the school was then in a most unsatisfactory condition, and Dr Keate (who took the degree of D.D. in 1810) took measures to improve it. He used birching to restore order and strengthen the authority of the masters. He retired in 1834.
- A.Clutton-Brock. "Eton" London: George Bell and Sons.
- "Keate, John (KT792J)". A Cambridge Alumni Database. University of Cambridge.
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Keate, John". Encyclopædia Britannica (11th ed.). Cambridge University Press.
- Maxwell Lyte, History of Eton College (3rd ed., 1899)
- Collins, Etoniana
- Harwood, Alumni Etonienses
- Annual Register (1852)
- Gentleman's Magazine (1852)