The United Kingdom of the Netherlands (1815–1839) (Dutch: Verenigd Koninkrijk der Nederlanden, French: Royaume-Uni des Pays-Bas) is the unofficial name used to refer to the Kingdom of the Netherlands (Dutch: Koninkrijk der Nederlanden, French: Royaume des Pays-Bas) during the period after it is first created from part of the First French Empire and before the new Kingdom of Belgium splits off from it in 1830.

This state, a large part of which still exists today as the Kingdom of the Netherlands, is made up of the former Dutch Republic (Republic of the Seven United Netherlands) to the north, the former Austrian Netherlands to the south, and the former Prince-Bishopric of Liège.

The House of Orange-Nassau comes to be the monarchs of this new state.The United Kingdom of the Netherlands collapses after the 1830 Belgian Revolution.

William I, King of the Netherlands, refuses to recognize a Belgian state until 1839, when he has to yield under pressure by the Treaty of London.

Only at this time are exact borders agreed.