The year 2012 marked the Diamond Jubilee of Elizabeth II being the 60th anniversary of the accession of Queen Elizabeth II on 6 February 1952. The only diamond jubilee celebration for any of Elizabeth's predecessors was in 1897, for the 60th anniversary of the accession of Queen Victoria.

Following the tradition of the Queen's Silver and Golden Jubilees, commemorative events were held throughout the Commonwealth of Nations. In comparison to the previous Golden Jubilee, events in the United Kingdom were significantly scaled back due to the economic policies of the governing Conservative Party deeming excessive cost to the taxpayer amidst widespread austerity as inappropriate.The Queen and the Duke of Edinburgh toured the United Kingdom and other members of the royal family toured the rest of the Commonwealth as the monarch's representatives. The Jubilee celebrations marked the beginning of the withdrawal of the Duke of Edinburgh from public life and a more prominent role for the Duke of Cambridge and Prince Harry in Commonwealth affairs.

Numerous events and tributes were held over the year and throughout the Commonwealth, culminating in a jubilee pageant held in London. The Queen Elizabeth Diamond Jubilee Trust was set up as a charitable foundation with a mission to leave a lasting legacy across the Commonwealth. Other projects included the Queen Elizabeth Diamond Jubilee Wood and the issuing of commemorative medals.

The Thames Diamond Jubilee Pageant was a parade on 3 June 2012 of 670 boats on the Tideway of the River Thames in London as part of the celebrations of the Diamond Jubilee of Elizabeth II. The Queen, Prince Philip and other members of the Royal Family were aboard vessels that took part in the parade. The parade was organised by the Thames Diamond Jubilee Foundation, and funded by private donations and sponsorship. The pageant master was Adrian Evans.The vessels that took part included military, commercial, and pleasure craft. According to Guinness World Records, this was the largest ever parade of boats, surpassing the previous record of 327 vessels set in Bremerhaven, Germany, in 2011. Sailing vessels and others too tall to pass under the bridges were moored as an "Avenue of Sail" downstream of London Bridge with smaller craft in St Katherine Docks.British media organisations estimated that one million spectators watched from the banks of the Thames The pageant was broadcast live by the BBC and Sky News and subsequently broadcast around the world on other networks. More than 10 million tuned into the BBC's four-and-a-half-hour coverage, with an audience average of 10.3 million.