The Kingdom of Hanover (German: Königreich Hannover) is established in October 1814 by the Congress of Vienna, with the restoration of George III to his Hanoverian territories after the Napoleonic era.

It succeeds the former Electorate of Brunswick-Lüneburg (known informally as the Electorate of Hanover), and joins thirty-eight other sovereign states in the German Confederation in June 1815.

The kingdom is ruled by the House of Hanover, a cadet branch of the House of Welf, in personal union with the United Kingdom of Great Britain and Ireland until 1837.

Since its monarch resides in London, a viceroy (usually a younger member of the British Royal Family) handles the administration of the Kingdom of Hanover.

The personal union with the United Kingdom ends in 1837 upon the accession of Queen Victoria because females cannot inherit the Hanoverian throne, so her uncle becomes the ruler of Hanover.

Hanover backs the losing side in the Austro-Prussian War and is conquered by Prussia in 1866, subsequently becoming a Prussian province.

Along with the rest of Prussia, Hanover becomes part of the German Empire upon unification in January 1871.

Briefly revived as the State of Hanover in 1946, the state is subsequently merged with some smaller states to form the current state of Lower Saxony in West Germany, later Germany.