He studied at the University of Paris.
After studies he became famous as a teacher of grammar and logic. Afterwards joining the order of St Dominic and turning his attention to theology, he was chosen provincial prior of his order in England in 1261, and in October 1272 Pope Gregory X terminated a dispute over the vacant archbishopric of Canterbury by appointing Kilwardby. Although the new archbishop crowned Edward I and his queen Eleanor in August 1274, he took little part in business of state, but was energetic in discharging the spiritual duties of his office.
In 1278 Pope Nicholas III made him cardinal-bishop of Porto and Santa Rufina; he resigned his archbishopric and left England, carrying with him the registers and other valuable property belonging to the see of Canterbury.
He was charitable to the poor.
Quotes from others about the person
Kilwardby's theological and philosophical views were summed up by David Knowles who said that he was a "conservative eclectic, holding the doctrine of seminal tendencies and opposing. .. the Aristotelian doctrine of the unity of form in beings, including man. "