Tillotson's reluctance to accept the see of Canterbury was overcome on 18 Oct. 1690, but he stipulated for delay, and that he should not be made ‘a wedge to drive out’ Sancroft. He was not nominated till 22 April 1691, elected 16 May, and consecrated 31 May (Whitsunday) in Bow church by Peter Mews [q. v.], bishop of Winchester, and five other bishops. Sancroft, who was still at Lambeth, refused to leave till the issue of a writ of ejectment on 23 June. Tillotson received the temporalities on 6 July, and removed to Lambeth on 26 Nov., after improvements, including ‘a large apartment’ for his wife. No wife of an archbishop had been seen at Lambeth since 1570.
His primacy was brief and not eventful. He exercised a liberal hospitality, and showed much moderation both to nonjurors and to nonconformists. He took no part in political affairs. No business was entrusted to convocation during his primacy. He seems to have initiated the policy of governing the church by royal injunctions addressed to the bishops; those of 13 Feb. 1689 were probably, those of 15 Feb. 1695 certainly, drawn up on his advice. Sharp consulted him about the case of Richard Frankland [q. v.], who had set up a nonconformist academy for ‘university learning.’ Tillotson replied (14 June 1692) that he ‘would never do anything to infringe the act of toleration,’ and then suggested, as ‘the fairest and softest way of ridding your hands of this business,’ that Sharp should explain to Frankland that the grounds for withdrawing a license were applicable also to conformists.
In 1693 appeared his four lectures on the Socinian controversy. He had delivered them at St. Lawrence Jewry in 1679–80, and now published them as an answer to doubts of his orthodoxy, based upon his intimacy with Thomas Firmin [q. v.], whose philanthropic schemes he had encouraged. His connection with Firmin had indeed been singularly close. He had acted as godfather to his eldest son (1665); as dean of Canterbury (1672) he had trusted him to find supplies for the lectureship at St. Lawrence Jewry; he now welcomed him to his table at Lambeth. The four lectures prove conclusively that Tillotson had no Socinian leaning; but their courteous tone and their recognition of the good temper of Socinian controversialists, ‘who want nothing but a good cause,’ gave offence. An incautious expression in a supplementary sermon on the Trinity (1693), missed by Leslie (Charge of Socinianism, 1695) but noted by George Smith (1693–1756) [q. v.], opened the way to the position afterwards taken by Samuel Clarke (1675–1729) [q. v.], assigning to our Lord every divine perfection, save only self-existence. Thus Tillotson unwittingly dropped the first hint of the Arian controversy, which arose on the exhaustion of the Socinian argument. Firmin employed Stephen Nye [q. v.] on a critique of Tillotson's lectures. Shortly before his death Tillotson read these ‘Considerations’ (1694), and remarked to Firmin, ‘My lord of Sarum shall humble your writers.’ Burnet's ‘Exposition’ was not published till 1699, but Tillotson had already revised the work in manuscript, and in one of the last letters he wrote (23 Oct. 1694) expresses his satisfaction, except on one point, the treatment of the Athanasian creed, adding, ‘I wish we were well rid of it.’ He revised also a portion of the ‘Vindication’ (1695) of his four sermons by John Williams (1634–1709) [q. v.]
At the end of 1687 Tillotson had received the warning of an apoplectic stroke. He was seized with paralysis in Whitehall chapel on Sunday, 18 Nov. 1694, but remained throughout the service. His speech was affected, but his mind clear. He is said to have recommended Tenison as his successor. During the last two nights of his life he was attended by Robert Nelson [q. v.], his correspondent from 1680 and his attached friend, though a nonjuror. He died in Nelson's arms on 22 Nov. 1694, and was buried on 30 Nov. in the chancel of St. Lawrence Jewry, where is a monument (erected by his widow) with medallion bust (engraved in Hutchinson's ‘Life’). Burnet preached a funeral sermon. He died penniless; ‘if his first-fruits had not been forgiven him by the king, his debts could not have been paid.’ His posthumous sermons afterwards sold for two thousand five hundred guineas. His library was put on sale, 9 April 1695, at fixed prices (see Bibliotheca Tillotsoniana, 1695).
He married (23 Feb. 1664) Elizabeth (d. 20 Jan. 1702), only child of Peter French, D.D. (d. 17 June 1655), by the Protector's sister Robina, who, after a year of widowhood, married, as her second husband, John Wilkins. Neither of his children survived him; his elder daughter, Mary (d. November 1687), married James Chadwick (d. 1697), and left two sons and a daughter (who married a son of Edward Fowler, D.D. [q. v.]); his younger daughter, Elizabeth, died in 1681. To Mrs. Tillotson, in accordance with a promise of William III, tardily fulfilled, was granted (2 May 1695) an annuity of 400l.; by the efforts of Dean William Sherlock [q. v.] and Robert Nelson this was increased (18 Aug. 1698) to 600l., enabling her