John Bird Sumner was a brother of Charles Richard Sumner, bishop of Winchester. Their father was Robert Sumner and their mother was Hannah Bird, a first cousin of William Wilberforce.
Sumner was born at Kenilworth, Warwickshire and educated at Eton College and King's College, Cambridge.
In 1802 he became a master at Eton and was ordained the following year. He was elected a fellow of Eton in 1817 and in 1818 the school presented him to the living of Maple Durham, Oxfordshire. After being a prebendary of the Durham diocese for some years, he was consecrated Bishop of Chester in 1828. During his episcopate many churches and schools were built in the diocese. In 1848 he was elevated to Archbishop of Canterbury (with an annual income of £15,000), and in this capacity he dealt impartially with the different church parties until his death.
His numerous writings were much esteemed, especially by the Evangelical party to which he belonged. His best known writings are his Treatise on the Records of Creation and the Moral Attributes of the Creator (London, 1816) and The Evidence of Christianity derived from its Nature and Reception (London, 1821).
In the well-known Gorham Case he came into conflict with Bishop Henry Phillpotts of Exeter (1778–1869), who accused him of supporting heresy and refused to communicate with him. He supported the Divorce Bill in parliament but opposed the Deceased Wife's Sister Bill and the bill for removing Jewish disabilities.
He was president of the Canterbury Association that founded Christchurch, New Zealand. In 1848 he was elected a Fellow of the Royal Society.
He died in 1862 at Addington and is buried in Addington churchyard. He had married Marianne, daughter of George Robertson, Captain RN.
- Chisholm, Hugh, ed. (1911). "Sumner, John Bird". Encyclopædia Britannica (11th ed.). Cambridge University Press