Halifax is a constituency^{[n 1]} represented in the House of Commons of the UK Parliament since 2015 by Holly Lynch of the Labour Party.^{[n 2]}

1918–1983: The County Borough of Halifax.

1983–2010: The Metropolitan Borough of Calderdale wards of Illingworth, Mixenden, Northowram and Shelf, Ovenden, St John's, Skircoat, Sowerby Bridge, Town, and Warley.

2010–present: The Metropolitan Borough of Calderdale wards of Illingworth and Mixenden, Northowram and Shelf, Ovenden, Park, Skircoat, Sowerby Bridge, Town, and Warley.

This constituency covers the large town of Halifax in West Yorkshire and includes the smaller town of Sowerby Bridge which adjoins Halifax but until 1974 was a separate Urban District.

The parliamentary borough was granted in the Great Reform Act 1832 and returned from that year until 1918 two members. A county borough recognized the density of the developed area in 1888 which provided most functions for inhabitants, retaining the West Yorkshire ceremonial county. The municipal or county borough was under a mayor, five aldermen and 45 councillors and had an area of 13,967 acres (56.52 km²).^[3]

At the time of the Norman Conquest, Halifax formed part of the extensive manor of Wakefield, which belonged to the king, but in the 13th century was in the hands of John Earl de Warrenne aka. Earl of Surrey (1231–1304).^{[n 3]} The prosperity of the town began with the first woollen products workshop established here in 1414, when there are said to have been only thirteen houses, which before the end of the 16th century had increased to 520.^[3] Camden, about the end of the 17th century, wrote that "the people are very industrious, so that though the soil about it be barren and improfitable, not fit to live on, they have so flourished ... by the clothing trade that they are very rich and have gained a reputation for it above their neighbours."^[4] The manufacturing standards and trade were improved by the arrival of certain merchants and clothworkers driven from the Spanish Netherlands by the persecution by the Duke of Alva.^[4]

Halifax was a borough by prescription^{[n 4]} rather than a medieval parliamentary borough, its privileges^{[n 5]} growing up with the increased prosperity brought by the cloth trade, but it was not incorporated until 1848. From 1832 until 1918 the town's property-qualifying residents paying scot and lot returned two members to parliament.^{[n 6][4]}

As of 2001, the town in the Pennines was relatively affluent, not afflicted by the high levels of unemployment, underemployment and crime seen in a few wards of the Yorkshire and Humber region but most constituents had modest incomes and there was some social housing in certain wards.^[5] Since 1987 the MP has represented the Labour Party; before that date for four years it was held by a Conservative MP, but generally since the Second World War it has been a Labour seat.

Prior to the 2017 general election, the Conservative Party launched its election manifesto at Dean Clough Mill in Halifax, and targeted the seat fairly heavily, for two years earlier the Labour majority in the constituency had fallen to just 428 votes, or 1% of the total vote. However, Lynch increased her majority by almost 5,000 votes, giving Labour its biggest majority in Halifax since 2001.

• List of parliamentary constituencies in West Yorkshire