大不列颠王国（英语：Kingdom of Great Britain），曾为英国历史上的正式国名，位于西欧大不列颠岛及其附属岛屿，存在于1707年至1800年。是根据《1707年联合法案》，由苏格兰王国与英格兰王国所共组的单一王国。新的单一政府与单一议会设于伦敦的西敏寺，而自从1603年苏格兰王詹姆士六世成为英格兰王詹姆士一世以来，这两个王国就有共同的君主。

当《1800年联合法案》通过以来，大不列颠王国又与爱尔兰王国合并，在1801年，大不列颠王国由大不列颠与爱尔兰联合王国取代。

The Kingdom of Great Britain, officially Great Britain /ɡreɪt ˈbrɪ.tən/, was a sovereign state in western Europe from 1 May 1707 to 31 December 1800. The state came into being following the Treaty of Union in 1706, ratified by the Acts of Union 1707, which united the kingdoms of England and Scotland to form a single kingdom encompassing the whole island of Great Britain and its outlying islands. It did not include Ireland, which remained a separate realm. The unitary state was governed by a single parliament and government that was based in Westminster. The former kingdoms had been in personal union since James VI, King of Scots, became King of England and King of Ireland in 1603 following the death of Queen Elizabeth I, bringing about a "Union of the Crowns". Also after the accession of George I to the throne of Great Britain in 1714, the kingdom was in a personal union with the Electorate of Hanover.