The coronation of George IV as King of the United Kingdom took place at Westminster Abbey, London, on 19 July 1821. Originally scheduled for 1 August of the previous year, the ceremony had been postponed due to the parliamentary proceedings of George's estranged wife, Queen Caroline; because these failed to deprive Queen Caroline of her titles and obtain a divorce from the King, she was excluded from the ceremony. In accordance with George's lavish personal tastes, the coronation was the most extravagant ever staged and a number of the traditional elements of the ceremonial were conducted for the last time.

The coronation of the monarch of the United Kingdom is an initiation ceremony in which they are formally invested with regalia and crowned at Westminster Abbey. It corresponds to the coronations that formerly took place in other European monarchies, which have all abandoned coronations in favour of inauguration or enthronement ceremonies. A coronation is a symbolic formality and does not signify the official beginning of the monarch's reign; de jure and de facto their reign commences from the moment of the preceding monarch's death or abdication, maintaining legal continuity of the monarchy.