The Chapel Royal is a group of clergy and musicians whose role is to serve the spiritual needs of the Sovereign. It has been in existence since before the Norman Conquest, and in its early years its function was mainly peripatetic, accompanying the Monarch around the country and indeed beyond: the Chapel Royal went with Henry V to Agincourt, where Mass was sung before the battle, and with Henry VIII to the Field of the Cloth of Gold. In Tudor times it played a major role in enhancing the splendour and magnificence of the court and the King, and in addition to their musical duties the Children were required to act in plays, masques and pageants to impress important visitors. This theatrical sideline developed through the Elizabethan period to the point where the Chapel could field a band of child players which was well-known to Shakespeare and Jonson, and Nathaniel Giles, Elizabeth I's master of the Children, was hauled before the Star Chamber and accused of recruiting talented actors to the Chapel who were, however, "noe way hable or fitt for singing". The Chapel had a unique role in the development of English church music, partly because it had the power to "impress" the best choristers from around the country, and partly because as the Monarch's private Chapel it was, to a certain extent at least, immune from the severe restrictions placed on the composition and use of music by the various religious reforms of the 16th and 17th centuries. It thus employed many leading musicians, including Cornyshe, Fayrfax, Tallis, Byrd, Gibbons, Blow, Purcell, Handel, S.S.Wesley and Arthur Sullivan.

During Tudor times the Chapel would follow the Sovereign around the country to whichever Palace or great house was in favour at the time. In Stuart times it came to rest at St James's and Whitehall Palaces, with a brief break during the Civil War when the Queen's Chapel was used as a stable by Cromwell. Since Whitehall Palace burned down in the late 17th century the Chapel Royal has been based exclusively at St James's Palace. There are two Chapels in the Palace complex. The Chapel Royal was built by Henry VIII and decorated by Hans Holbein in honour of his Master's short-lived fourth marriage to Anne of Cleves. Mary I's heart is buried beneath the choir-stalls: Elizabeth I waited for news of the defeat of the Armada from the Royal pew at the back of the Chapel: Charles I spent his last night in the room up a winding staircase in the gatehouse now used as the choir practice room, descending for Communion in the Chapel and the walk across the park to his execution: later in the 17th century the same room was requisitioned as a bedroom by Henry Purcell who often put up his impecunious friend John Dryden, fleeing his creditors: Queen Victoria was married in the Chapel, and her marriage certificate, hand-written by the Archbishop of Canterbury and signed by both bride and groom, hangs on the wall in the vestry.

The Queen's Chapel, across the road from the Chapel Royal, was built by James I for the putative Catholic bride of his son, later Charles I, and designed by Inigo Jones. Grinling Gibbons and Christopher Wren also had a hand in the decoration. The Chapel was used by the Catholic Queen Henrietta Maria until the outbreak of the Civil War, and in later centuries was the home of the Danish Church in London