He was a son of Thomas Hales of Hales Place, Halden, Kent. He was brought up by Christopher Hales, his uncle or more distant relative. Without university education, he learned Latin, Greek, French, and German. He was lamed by an accident in youth, and was often called ‘club-foot’ Hales. Dissatisfied with working under Christopher Hales, he wrote in 1534 to Thomas Cromwell, asking for employment. Taken on in some capacity by 1535, he struck up a lasting friendship with Ralph Sadler, and in 1537 became secretary to Sir John Gostwick. He may have been Clerk of the Hanaper for Henry VIII, and was deputy to Ralph Sadler, as Master of the Great Wardrobe in 1545.

He was the founder of a free grammar school at Coventry, based on the grant in 1545 of St. John's Hospital, Coventry and its property; it is now King Henry VIII School, Coventry. In political life Hales, who was member of parliament for Preston, was specially concerned with opposing the enclosure of land, being the most active of the commissioners appointed in 1548 to redress this evil; but he failed to carry several remedial measures through parliament.

When the protector, Edward Seymour, 1st Duke of Somerset, was deprived of his authority in 1550, Hales left England and lived for some time at Strassburg and Frankfort, returning to his own country on the accession of Elizabeth I. However he soon lost the royal favour by writing a pamphlet, A Declaration of the Succession of the Crowne Imperiall of Inglande, which declared that the recent marriage between Lady Catherine Grey and Edward Seymour, earl of Hertford, was legitimate, and asserted that, failing direct heirs to Elizabeth, the English crown should come to Lady Catherine as the descendant of Mary, daughter of Henry VII of England.

Hales was imprisoned, but was quickly released. He was the Member of Parliament for Lancaster from 1563 to 1567.

He wrote his Highway to Nobility about 1543. He wrote Introductiones ad grammaticam for his newly-founded school.