The county of West Sussex is divided into 9 parliamentary constituencies: 2 borough constituencies and 7 county constituencies, one of which crosses the county border with East Sussex.
The Local Government Act 1972 moved the District of Mid Sussex into West Sussex from East Sussex. This change was put into effect in the Parliamentary constituency boundaries for the 1983 boundary changes.
Under the fifth periodic review of Westminster constituencies, the Boundary Commission for England decided to retain the existing 8 constituencies in West Sussex, with minor changes to realign constituency boundaries with those of current local government wards, and to reduce the electoral disparity between constituencies.
See 2023 review of Westminster constituencies for further details.
For the 2023 review of Westminster constituencies, which redrew the constituency map ahead of the 2024 United Kingdom general election, the Boundary Commission for England opted to combine West Sussex with East Sussex as a sub-region of the South East Region, resulting in the creation of a new cross-county boundary constituency named East Grinstead and Uckfield.
The following constituencies were proposed:
Containing electoral wards from Adur
Containing electoral wards from Arun
Containing electoral wards from Chichester
Containing electoral wards from Crawley
Containing electoral wards from Horsham
Containing electoral wards from Mid Sussex
Containing electoral wards from Worthing
Primary data source: House of Commons research briefing - General election results from 1918 to 2019
The number of votes cast for each political party who fielded candidates in constituencies comprising West Sussex in the 2019 general election were as follows:
<sup>1</sup>1983 & 1987 - SDPâÂÂLiberal Alliance
<nowiki>*</nowiki> Included in Other
A cell marked â (with a different colour background to the preceding cell) indicates that the previous MP continued to sit under a new party name.
The Local Government Act 1972 moved the District of Mid Sussex into West Sussex from East Sussex. This change was put into effect in the Parliamentary constituency boundaries for the 1983 boundary changes.
From 1885 to 2019, only two MPs had won elections who were not members of the Conservative Party: one Liberal MP in 1923 and one Labour MP in 1997, 2001 and 2005. This changed in 2024, with 3 Labour MPs and 3 Liberal Democrat MPs being elected.