Miss United Kingdom is a title held by the highest-ranked contestant from the UK in the Miss World pageant. The winner sometimes competes at Miss International and Miss Supranational the following year under the Britain, England or United Kingdom banner. From 1958 to 1999, Miss United Kingdom was a national beauty pageant held to choose a representative for the Miss World Pageant. In 1999, Scotland and Wales had their own contestants at Miss World, and in 2000, England and Northern Ireland sent their own representatives. The existing organization now runs the Miss England competition.

The pageant was created in 1958 by Eric Morley, the man behind the Miss World pageant. Before 1958, the winner of the Miss Great Britain contest would go on to represent the UK at the Miss World pageant, but from 1952 to 1957, none of the Miss GB title holders made the final seven at Miss World, so Morley decided to create the Miss United Kingdom contest in the hope of achieving better results at Miss World. From 1958 to 1999, the winner of Miss United Kingdom title would represent the UK at Miss World.

At Miss United Kingdom, traditionally there would be regional heats from the four constituent Countries of the United Kingdom, these would take place early in the year. The winners of the respective Miss England, Miss Scotland and Miss Wales titles would compete in the summer at Miss Universe. The Miss UK contest would then take place featuring these titleholders plus a certain number of other top contestants from the regions, the winner would then go on to compete at the Miss World Contest in October/November. This meant that during the 60s, 70s and 80s, many British beauty queens competed at both the Miss Universe and Miss World contests.

Although England, Scotland, Wales and Northern Ireland have had separate representatives in other international pageants, Miss World did not allow this until the creation of separate Parliaments in the United Kingdom.

1999 was the year of the last Miss United Kingdom pageant, won by Nicola Willoughby, who competed as Miss UK at Miss World (the final woman to do so). The 1999 Miss World contest also saw the debuts of Scotland (represented by Stephanie Norrie) and Wales (represented by Clare Marie Daniels), so there was the unusual situation of having a Miss UK compete alongside Miss Scotland and Miss Wales. The following year, Julie Lee-Ann Martin became the first representative of Northern Ireland in the pageant while Michelle Walker was the first to compete as Miss England.

Since 2000, the Miss World Organization has announced the highest-ranking delegate of the four home nations at Miss World, as the winner of the Miss United Kingdom title. The winner receives a cash prize and has often represented the United Kingdom at the Miss International contest the following year. Since 2000, Scotland has the most Miss United Kingdom winners with (9), followed by England (6), then Wales (4), and ending with Northern Ireland (3).

^* Real name Diane Hickingbotham
^** Also known as Carolyn Grant

From 1952 to 1957 the UK were represented by the winner of the Miss Great Britain pageant. At the first Miss World in 1951, 21 of the 26 contestants were from the UK, including those that placed as first runner-up and second runner-up. From 1958 to 1999 the winner of the Miss United Kingdom pageant competed. There have been five UK winners of the Miss World title; all won the title competing as Miss United Kingdom.