Watford is a constituency represented in the House of Commons of the UK Parliament since 2019 by Conservative Party MP Dean Russell.

Hertfordshire was a county constituency covering the county of Hertfordshire in England. It returned two Knights of the Shire to the House of Commons of England until 1707, then to the House of Commons of Great Britain until 1800, and to the House of Commons of the Parliament of the United Kingdom from 1801 until 1832. The Reform Act 1832 gave the county a third seat with effect from the 1832 general election.