Armagh or County Armagh was a Parliamentary Constituency in the House of Commons. It was replaced in boundary changes in 1983.

The Act of Union 1800 provided for the Parliament of Ireland to be merged with the Parliament of Great Britain, to form the Parliament of the United Kingdom. The 300 seats in the Irish House of Commons were reduced to 100 Irish members in the United Kingdom House of Commons. The thirty-two Irish counties retained two seats in Parliament.