John Harley (29 September 1728 – 7 January 1788) was a British bishop.
Harley was the second son of Edward Harley, 3rd Earl of Oxford and Earl Mortimer. He was Archdeacon of Shropshire from 1760 to 1769 and then Archdeacon of Hereford from 1869 to 1787. He was Dean of Windsor, Registrar of the Order of the Garter and briefly, at the end of his life, the Bishop of Hereford.
His son Edward (by his wife Roach Vaughan, daughter of Gwynne Vaughan of Trebarry, Radnorshire) succeeded Harley's elder brother (Edward) as 5th Earl of Oxford.