Carlow was a parliamentary constituency in Ireland, represented in the House of Commons of the United Kingdom of Great Britain and Ireland. It returned one Member of Parliament (MP) from 1801 to 1885.
This constituency was the parliamentary borough of Carlow in County Carlow. It succeeded the two-seat constituency of Carlow in the Irish House of Commons. Its one MP was chosen by lot to sit in the First Parliament of the United Kingdom in 1801.
The borough was defined by the Parliamentary Boundaries (Ireland) Act 1832 as:
It was disfranchised by the Redistribution of Seats Act 1885, becoming part of the constituency of County Carlow.
Notable MPs for Carlow included F. J. Robinson, later Prime Minister of the United Kingdom as Viscount Goderich, the zoologist Nicholas Aylward Vigors, and the historian and writer John Dalberg-Acton, later known as Lord Acton.
Maule was appointed as Baron of the Exchequer in England, requiring a by-election.
After meeting 59 times, an election committee amended the poll to 160 for Gisborne and 159 for Bruen and, in July 1839, Gisborne was declared elected.
Sadleir was appointed a Lord Commissioner of the Treasury, requiring a by-election.