Acts of Union creating Great Britain

The Acts of Union 1800 (Irish: Achtanna an Aontais 1800) were parallel acts of the Parliament of Great Britain and the Parliament of Ireland which united the Kingdom of Great Britain and the Kingdom of Ireland (previously in personal union) to create the United Kingdom of Great Britain and Ireland. The acts came into force between 31 December 1800 and 1 January 1801, and the merged Parliament of the United Kingdom had its first meeting on 22 January 1801.

Provisions of the acts remain in force, with amendments and some Articles repealed, in the United Kingdom, but they have been repealed in their entirety in the Republic of Ireland.