Haverfordwest was a parliamentary constituency. It returned one Member of Parliament (MP) to the House of Commons of the Parliament of the United Kingdom, elected by the first past the post system.

The constituency was enfranchised in 1545, as the second borough constituency in the historic county of Pembrokeshire. In the previous election of 1542, the first at which Wales is known to have sent members to the Parliament of England, this borough was one of the ancient boroughs contributing to the wages and being in some sense represented by the member for Pembroke.

During the eighteenth century, Haverfordwest was considered to be little more than a pocket borough for the Philipps family of Picton Castle.^[1]

From 1832 to 1885, it was a district of boroughs constituency, consisting of the three boroughs of Haverfordwest, Fishguard and Narberth.^[2]

The constituency was abolished for the 1885 general election, and merged into the newly created constituency of Pembroke and Haverfordwest.