Mallow was a United Kingdom Parliament constituency in Ireland, returning one MP. It was an original constituency represented in Parliament when the Union of Great Britain and Ireland took effect on 1 January 1801. The constituency lasted until 1885 when it was absorbed into the North East Cork constituency.

Prior to the Union, the Mallow constituency had been represented in the Parliament of Ireland.

This constituency was a parliamentary borough based on the town of Mallow in County Cork. From the 1801 union until 1832, the boundaries and franchise were the same as in the previous Parliament of Ireland constituency, namely all freeholders within the manor of Mallow. The manor comprised the portion of the civil parish of Mallow north of the River Blackwater, as well as three townlands south of the Blackwater – namely Lower (or North) Quartertown, Upper (or South) Quartertown, and Gortnagraiga – which constituted the portion of the civil parish of Mourne Abbey within the barony of Fermoy.^[1][2] For all Irish borough constituencies, the Representation of the People (Ireland) Act 1832 changed the franchise and the ancillary Parliamentary Boundaries (Ireland) Act 1832 defined new boundaries, in most cases accepting the recommendations of a committee appointed the previous year.^[1] Mallow was one such case, despite protests from the gentry who would be disenfranchised.^[3][4] The new boundary was:^[1][5]

From the Easternmost Gate Post (opposite the Park Wall of Mr. [Richard Harris-^[6]]Purcell) of a Field on the Kanturk Road, the Entrance to which is distant about One hundred and seventy-six Yards (measured along the Kanturk Road) from the Seneschal's House, in a straight Line to the Gate Post nearest the Turnpike in a Wall on the Southern Side of the old Road which runs a little to the North of the Limerick Road, and which Post is distant about Two hundred and forty-two Yards (measured along the said old Road) to the North-west of the Turnpike; thence in a straight Line to the Point at which a Bye Lane joins the Fair-lane Road, about One hundred and fifty Yards to the North of the Entrance to the Lime and Salt Works; thence in a straight Line to the Point at which the Carrigoon Road, which passes under Mr. [Denham] Jephson's Park Wall,^[7] is met by a Fence which divides a Field occupied by Mr. Lynch from a Field occupied by Mr. Carmichael, and which Point is also about Three hundred and seventy-five Yards to the North of a small Door in the Park Wall; thence in a straight Line across the Park to the Westernmost Point at which the Boundary of Mr. [Robert^[8]] Delacour's Pleasure Grounds meets the Fermoy Road; thence, Westward, along the Boundary of Mr. Delacour's Pleasure Grounds to the Southernmost Point at which the same meets the Boundary of the Garden attached to the Water Mill; thence in a straight Line to a Point in the old Cork Road which is distant Two hundred and twenty-five Yards (measured along the old Cork Road) to the South of the old Turnpike thereon; thence in a straight Line to a Point on the new Cork Road which is distant about Two hundred and ninety Yards (measured along the new Cork Road) to the South of the said old Turnpike, and which Point is at the Commencement of a Nursery Ground; thence in a straight Line in the Direction of the Eastern Corner of Captain Davis's House to the Point at which such straight Line cuts the Blackwater River; thence in a straight Line to the Gate Post first described.

This excluded a large rural hinterland but included the Ballydaheen suburb immediately south of the Blackwater.^[2] The new boundary appears on the Ordnance Survey of Ireland's 1878 town plan of Mallow.^[9]