On 1 March 1966 the Government announced its decision to adopt a decimal currency system. The task of striking the hundreds of millions of new coins in readiness for decimalisation in 1971 made the construction of a new Mint essential. Llantrisant was chosen as the location for the new Mint and, the first phase of building having been completed, was opened by the Queen in December 1968.

By 1971 the second phase of construction at the Royal Mint in Llantrisant was approved and the factory was working at full speed making 60,000,000 coins per week for both the United Kingdom and overseas. Tower Hill ceased production in 1975 and the occasion was marked by the ceremonial striking of the last coin.

The 1980s saw unprecedented changes to the coinage of the United Kingdom with the addition of the £1, 20p and nickel-brass £2 coins and the removal of the 1/2p from circulation. A new Precious Metal Unit was opened in 1986 by Princess Diana and the range of bullion coins was extended by the introduction of the gold Britannia the following year.

The 1990s saw further technological advance as additional plating facilities were commissioned, and computers and computer-aided design systems were installed along with new high-speed coining presses. The Mint celebrated the 25th anniversary of its move to Llantrisant and with the withdrawal of old-size 5p and 10p pieces all coins in circulation now bear the portrait of the Queen.

The first ten years after the millennium saw the Royal Mint creating a new Great Seal of the Realm and changing the definitive designs on United Kingdom coins. In addition it vested from government to become a company.

The Royal Mint struck Olympic Medals for the first time in our history in 2012. This was accompanied by a highly successful series of Olympic collector coins, creating real interest as people were able to collect them from their change. Commemorative coins have continued to be a success and the Mint has diversified into new areas such as bullion and gifting, with the site becoming a visitor attraction in 2016 after the opening of the Royal Mint Experience.