Armagh was an Irish constituency in the House of Commons of the United Kingdom from 1801 to 1885.

The parliamentary borough of Armagh in County Armagh was one of 33 Irish boroughs which were retained under the Acts of Union 1800.^[1] It was the successor to the two-seat constituency of Armagh in the Irish House of Commons.^[2] Its one MP in 1801 was chosen by lot to sit in the First Parliament of the United Kingdom.

Under the Parliamentary Boundaries (Ireland) Act 1832, it was defined as:^[3]

From Mr. Carroll's Windmill on the West of the City in a straight Line in the Direction of the Spire of Grange Church to the Point at which such straight Line cuts the new Dungannon Road; thence in a straight Line in the Direction of the Eastern Dome of the Observatory to the Point at which such straight Line cuts the Boundary of the Grounds attached to the Observatory; thence, Eastward, along the Boundary of the Grounds of the Observatory to the Point at which the same meets the Road to the Deanery; thence in a straight Line to the Magazine near the Infantry Barracks; thence in a straight Line, through a Point on the Rich Hill Road which is distant Twenty-five Yards (measured along the Rich Hill Road) to the East of the South-eastern Corner of the Infantry Barracks, to a Point which is One hundred and thirty Yards beyond the said Point on the Rich Hill Road; thence in a straight Line in the Direction of the South-eastern Angle of the Palace to the Point at which such straight Line cuts the Demesne Wall; thence, Northward, along the Demesne Wall to the Point at which the same leaves the Boundary of the Corporation Land; thence, Northward, along the Boundary of the Corporation Land to the Point at which the same meets the Monaghan Road; thence in a straight Line to Mr. Carroll's Windmill.

The constituency was disenfranchised under the Redistribution of Seats Act 1885, which took effect at the 1885 general election.^[4] The borough of Armagh, as part of the barony of Armagh, became part of the county division of Mid Armagh.^[5]