1989–90 Sussex County Football League

The 1989–90 Sussex County Football League season was the 65th in the history of Sussex County Football League a football competition in England.

Division One
Division One featured 16 clubs which competed in the division last season, along with two new clubs, promoted from Division Two:
 * Ringmer
 * Seaford Town

Also, Haywards Heath changed name to Haywards Heath Town.

Division Two
Division Two featured eleven clubs which competed in the division last season, along with five new clubs.
 * Clubs relegated from Division One:
 * Oakwood
 * Portfield
 * Clubs promoted from Division Three:
 * Franklands Village
 * Saltdean United
 * Stamco

Division Three
Division Three featured ten clubs which competed in the division last season, along with four new clubs:
 * Buxted
 * East Grinstead, relegated from Division Two
 * Town Mead
 * Withdean

Also, Falcons changed name to Rottingdean.