Hale was the son of Robert Hale, a barrister. Orphaned at the age of five, he was educated according to Puritan principles under the direction of his guardian, until he enrolled at Magdalen College, Oxford, in 1626, with the intention of taking holy orders. He soon changed his mind and began to devote most of his time to fencing, gambling, and other diversions; at one time he considered enlisting as a soldier in the service of Frederick Henry, prince of Orange. A consultation with an eminent lawyer on family business so impressed him that he chose the law as his profession. In 1628 he was admitted to Lincoln's Inn, where he studied under the guidance of John Selden (Selden, John), one of the leading jurists and scholars of his age, who extended his studies to include Roman law, English history, mathematics, and natural philosophy. Called to the bar in 1637, he soon had a flourishing practice.

Hale remained aloof from the Long Parliament's opposition in the 1640s to King Charles I and avoided taking sides during the Civil Wars between the king and Parliament. Nevertheless, he defended many Royalists, most notably Archbishop William Laud, who had persecuted Puritan churchmen; and he probably advised Thomas Wentworth, 1st Earl of Strafford, who was impeached by the House of Commons on charges of high treason, and later Charles I during his trial. In spite of his support of the Royalists, in 1649 he took the oath of fidelity to the republican Commonwealth and, later in 1654, was persuaded by his Royalist friends to accept a judgeship from Oliver Cromwell (Cromwell, Oliver), now lord protector. In 1651 and 1652, he was active in the law-reform movement and contributed much to the work of the committee that advised Parliament on far-reaching improvements in the law and legal system of the time. On Cromwell's death he refused to continue as judge and was returned to Parliament as member for Oxford. He took a prominent part in the proceedings of the Convention Parliament, called after the dissolution of the Long Parliament, and in promoting the restoration of Charles II.

In 1660 Hale was appointed chief baron of the Exchequer, the court principally concerned with matters of crown revenue, and in the same year he was knighted. Between 1666 and 1672 he spent much time on the statutory tribunal that resolved disputes between owners and tenants of property destroyed in the Great Fire of London in 1666. In 1671 he became chief justice of the King's Bench, an office he relinquished in 1676 when his health began to fail.

Hale's work on the Bench—in an age when these attributes were not common even among judges—was characterized by singular personal integrity and impartiality. He acted, moreover, with scrupulous fairness toward prisoners. The one point on which he was criticized by later writers was his belief in witchcraft, and he once permitted the execution of two women accused as witches. Hale was tolerant in religious matters and on numerous occasions mitigated the rigours of the law against dissenters from the Church of England. Throughout his life he retained his Puritan sympathies and numbered among his intimate friends prominent nonconformists. Evenhanded also in his friendships, he maintained ties with Anglican bishops as well.

Lord Chancellor Nottingham (the other outstanding legal figure of Hale's generation) wrote of him that

But Hale is principally remembered not as a judge but as a jurist. He was a prodigious searcher of legal records and formed an extensive collection of manuscripts and transcripts. The bulk of this collection is now deposited in the library of Lincoln's Inn. On the basis of these manuscripts and transcripts he wrote numerous books and treatises, though he published little of his own legal work during his lifetime; some of his treatises were printed posthumously, others still remain unpublished. The published work by which he is perhaps best known is his History of the Pleas of the Crown (the House of Commons directed in 1680 that it be printed, though it was not published until 1736). This work remains one of the principal authorities on the common law of criminal offenses. But he also wrote widely on topics of constitutional and civil law, as his editorial talent enabled him to analyze and rearrange the jumbled collection of 17th-century and earlier law materials. When Sir William Blackstone (Blackstone, Sir William) wrote his classic Commentaries on the Laws of England (1765–69), he found that he could not do better than adopt Hale's “Analysis of the Civil Part of the Law.”

Hale's literary talent was enhanced by his considerable critical faculty. He was both a historian and a critic of the law, and his writings take stature from his talents as historian and critic. His place is undoubtedly among the principal figures in the history of English common law.