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.

Hertford was the name of a parliamentary constituency in Hertfordshire, which elected Members of Parliament (MPs) from 1298 until 1974.