After the Romans left Britain in the early 5th century the country descended into chaos. It was not until the 7th century that Anglo Saxon kings established mints within their kingdoms. By the time of Aethelred II who reigned from 978-1016 there were mints in 70 towns and cities. By the end of the 13th century the minting resources of London were concentrated within the walls of the Tower of London. The coins were struck by holding a metal blank between two engraved dies and striking the top die with a hammer, hence they are called "Hammered" coins. In 1279 the number of mints in England was reduced, and a unified system was established, run from the London mint. Thereafter, only a few local and episcopal mints continued to operate intermittently, and by 1553 English minting was wholly concentrated in a single establishment. Thenceforward, save during the Civil War and the existence of temporary country mints during the recoinage of the 1690s, one mint served England, Wales and Ireland.

In 1660 the restored King Charles II brought new coin-making technology from Holland and hammering was replaced by rolling mills and screw presses, which produced coins more quickly and to higher quality. These were known as "Milled" coins. In 1696 the great scientist Sir Isaac Newton became Warden of the Royal Mint. His first task was to address the problems of forgery and the circulation of inferior hammered silver coins, much of which was clipped and badly worn. To this end he supervised the great recoinage of 1696. In 1699 he became Master of the Royal Mint, a position he held until his death in 1727.

From 1710 it also served Scotland since, following the Act of Union which provided for coin of the same standard and value throughout the United Kingdom, the Edinburgh mint closed on 4 August that year, though it was not formally abolished until 1817. The Royal Mint worked independently until control by the Treasury was established after 1688.

The organisation as established in 1279 endured in form until the nineteenth century. At first the warden was the monarch's immediate representative in the Mint, and all coin or bullion reached the Mint through him. He was constituted a magistrate and judge for all matters affecting the Mint and it was his duty to act against counterfeiters or clippers of coin. He also collected the dues of the Mint and defrayed and accounted for its expenditure until, under the Coinage Act 1666, the master, first appointed in 1278, replaced the warden as the effective head of the Mint. From 1680 to 1686 the office of master was executed by a Mint Commission. In 1787 a Committee of the Privy Council on Coin was set up as a result of the parlous state of the currency and alleged negligence of masters of the Mint. Its membership was widened in 1798 and for the following 16 years this body assumed the major responsibility for Mint administration. It was wound up in 1816 but its recommendations led to the recoinage and reorganisation of the Mint after the Napoleonic Wars.

In 1797 Matthew Boulton won a contract to produce coins, including the "Cartwheel" one-penny and two-penny pieces, for the Royal Mint. The coins were of outstanding quality, struck using the latest steam presses. The Royal Mint decided to adopt the new steam powered technology, but the Tower premises were too small, with additional space being required, the Royal Mint left the Tower at the beginning of the nineteenth century and moved to a purpose-built facility on nearby Tower Hill. In the 1880s the factory buildings were reconstructed and extended. Further rebuilding was undertaken at the turn of the century with steam giving way to electricity. The work of construction and renovation became a continuous process as the Royal Mint endeavoured to cope with the enormous increase in its output. By the 1960s little of the original mint remained, apart from the dignified main building and the massive gatehouses which still stand today.

After World War II the next great challenge facing the Royal Mint was decimalization of the UK coinage. During the 1960s the movement gathered momentum and on 1st March 1966 the Government announced the impending changeover to decimal coinage. In 1968 the Royal Mint introduced 5p and 10p coins, the same size and value as existing one-shilling and two-shilling coins. In 1969 came the brand new 50p piece, designed to replace the ten-shilling banknote. "D-Day" itself came on 15th December 1971 and went off amazingly smoothly. The old penny and three-penny bit were withdrawn sooner after and the sixpence followed in 1980. The £1 coin arrived in 1983, while the 5p 10p and 50p coins were re-sized in the 1990s. The British two pound (£2) coin was first issued as a commemorative coin in 1986 to celebrate the Commonwealth Games in Scotland. Six further commemorative issues followed between 1989 and 1996. These coins did not circulate in large numbers. After a review of the United Kingdom coinage, it was decided that a general-circulation £2 coin was needed, and a new bi-metallic design was issued on 15 June 1998 (dated 1997). The need to mint hundreds of millions of new coins, and meet the growing demand from overseas customers, meant that the Tower Hill mint was inadequate. In December 1968 the Queen opened the first phase of the new Mint production facility at Llantrisant, south Wales, where production was progressively transferred over the next seven years. The last coin, a gold sovereign, was struck at Tower Hill in November 1975.