He was born at Chertsey in Surrey, and was educated at Eton College and at Magdalen College, Oxford, becoming demy or scholar in 1619, and fellow in 1625. He took holy orders in 1629, and in 1633 in preaching before the court he won the approval of the Earl of Leicester and was presented with the living of Penshurst in Kent. In 1643 he was made archdeacon of Chichester. He was a member of the convocation of 1640, and was nominated one of the Westminster Assembly of divines. Instead of sitting in parliament, he took part in the unsuccessful rising at Tunbridge in favour of King Charles I, and was obliged to flee in disguise to Oxford, then the royal headquarters.
There he spent much of his time writing, though he accompanied the king's commissioners to London, and afterwards to the ineffectual convention at Uxbridge in 1645, where he disputed with Richard Vines, one of the parliamentary envoys. In his absence he was appointed canon of Christ Church, Oxford and public orator of the university. These dignities he relinquished for a time in order to attend the king as chaplain during his captivity in the hands of the parliament. When Charles was deprived of all his loyal attendants at Christmas 1647, Hammond returned to Oxford and was made subdean of Christ Church, only, however, to be removed from all his offices by the parliamentary visitors, who imprisoned him for ten weeks.
Afterwards he was permitted, though still under quasi-confinement, to live at the house of Philip Warwick at Clapham in Bedfordshire. In 1650, now free, Hammond betook himself to the friendly mansion of Sir John Pakington, at Westwood, in Worcestershire, where he died on the eve of his promotion to Bishop of Worcester. Hammond was held in high esteem even by his opponents. He was an excellent preacher; Charles I pronounced him the most natural orator he had ever heard. He read widely, and was a diligent scholar.
His writings, published in 4 vols. fol. (1674 - 1684), consist mostly of controversial sermons and tracts. The Anglo-Catholic Library contains four volumes of his Miscellaneous Theological Works (1847 - 1850). The best of them are his Practical Catechism, first published in 1644; his Paraphrase and Annotations on the New Testament; and an incomplete work of a similar nature on the Old Testament. His Life, a delightful piece of biography, written by Bishop John Fell, and prefixed to the collected Works, was reprinted in vol. iv. of Wordsworth's Ecclesiastical Biography.