His father John Stearne of Cambridge, who settled in County Down and married Mabel Bermingham, a niece of Ussher, was a remote relation of Archbishop Richard Sterne.
On the outbreak of the Irish Rebellion of 1641, Stearne left for England, and in 1643 went to Cambridge, where he studied medicine at Sidney Sussex College and collected material for his first work, Animi Medela.
He remained at Cambridge for about seven years and then spent some time at Oxford, where he was welcomed by Seth Ward, then fellow of Wadham College.
In 1667, a charter was granted to the College of Physicians, under which a governing body of fourteen fellows was constituted—of whom Sir William Petty was one—with Stearne at their head as president for life.
He was buried, by his own request, in the chapel of Trinity College, where his epitaph, by his friend Henry Dodwell the elder, described him as Philosophus, Medicus, summusque Theologus idem.