Until the 1885, the seat was constituted as a Parliamentary Borough, sending two MPs (burgesses) to the House of Commons up to 1832, when its representation was reduced to one member by the Reform Act 1832.

The constituency (including the two versions under other names) was held by members of the Conservative Party from 1880 to 2024, when it was taken by the Liberal Democrats at the 4th July general election.

[2] Edward Turnour held the seat for 47 years from a 1904 byelection until the 1951 general election, which included the whole period of Horsham and Worthing's existence.

2010–2024: The District of Horsham wards of Billingshurst and Shipley, Broadbridge Heath, Denne, Forest, Holbrook East, Holbrook West, Horsham Park, Itchingfield, Slinfold and Warnham, Nuthurst, Roffey North, Roffey South, Rudgwick, Rusper and Colgate, Southwater, and Trafalgar, and the District of Mid Sussex wards of Ardingly and Balcombe, Copthorne and Worth, and Crawley Down and Turners Hill.

2024–present: The District of Horsham wards of Billingshurst, Broadbridge Heath, Colgate & Rusper, Cowfold, Shermanbury & West Grinstead, Denne, Forest, Holbrook East, Holbrook West, Itchingfield, Slinfold & Warnham, Nuthurst & Lower Beeding, Roffey North, Roffey South, Rudgwick, Southwater North, Southwater South & Shipley, and Trafalgar.