This article needs additional citations for verification. (July 2007) (Learn how and when to remove this template message)
After an undergraduate career at Lincoln College, Oxford and St Alban's Hall he was elected a Fellow of Brasenose College, Oxford in 1740 and was ordained as a priest; he was Rector of the College living of Wapping 1748-1800. He resigned his Fellowship in 1750, as he had to do on marriage.
His chief interest was medicine and he received the degrees of Bachelor and Doctor of Medicine from Oxford in 1759. He served as a hospital physician in Lincoln, where his success with the mentally ill led to him treating such patients in his own home. When George III had his first attack of madness (often now identified as porphyria) in 1788 Willis was recommended to the Queen by an equerry's wife, whose mother he had treated successfully.
Willis' treatment of the King included many of the standard methods of the period, including coercion, restraint in a strait jacket and blistering, but there was also more kindness and consideration for the patient than was usual. The King's recovery in 1789 made Willis' reputation and he had to open a second establishment to accommodate the numbers of patients seeking his help.