On 11 April 1670 he succeeded Gunning as Master of St John's, Cambridge; he was vice-chancellor in 1678, and resigned his mastership, "because of a faction," at Christmas 1679.

He was consecrated Bishop of Rochester, at Lambeth on 11 November 1683, holding his deanery in commendam, with the office of Lord High Almoner.

On 16 July 1684 he was translated to Ely (confirmed 23 August) in succession to Gunning, who had made him one of his literary executors.

Turner's obligations to James did not prevent him from joining in the petitionary protest (18 May 1688) of the seven bishops against the king's declaration for liberty of conscience.

He professes to write "in behalf of my elder brother, and the rest of my nearest relations, as well as for myself" (meaning William Sancroft and the other nonjuring bishops).

His intestacy gave all his effects to his daughter Margaret (died 25 December 1724), wife of Richard Gulston of Wyddial Hall, Hertfordshire, thus disappointing the expectation of bequests to St John's College, of which he had already been a benefactor.

Turner is an ancestor of Henrietta Euphemia Tindal (née Harrison), a 19th-century poet and novelist,[3] who was the great-granddaughter of a later Richard Gulston of Wyddial Hall, and of the Tindal-Carill-Worsley family.