South West Hertfordshire is a constituency[n 1][n 2] in the House of Commons of the UK Parliament, represented since 2019 by Gagan Mohindra, a Conservative.

[3] The constituency surrounds the constituency (and town) of Watford on three sides, taking in the town of Rickmansworth and the villages of Abbots Langley, Chorleywood, Croxley Green, Heronsgate, Kings Langley, Leavesden, Loudwater, Maple Cross and South Oxhey.

The parts of the District of Dacorum, including Berkhamsted, were transferred from the abolished constituency of Hemel Hempstead.

Kings Langley transferred to a re-established Hemel Hempstead, Bedmond to St Albans, and three further wards in the Three Rivers District to Watford.

The parts of the District of Three Rivers not previously within the constituency were transferred primarily from Watford, with a small area from St Albans.