On 26 August 1747 Whytt was appointed professor of the theory of medicine in Edinburgh University. On 16 April 1752 Whytt was elected Fellow of the Royal Society of London, and contributed to the "Philosophical Transactions". In 1756 he gave lectures on chemistry in the university in place of John Rutherford (1695–1779). In 1761 Whytt was made first physician to King George III in Scotland—a post specially created for him—and on 1 December 1763 he was elected president of the Royal College of Physicians of Edinburgh; he held the presidency till his death at Edinburgh on 15 April 1766.