The 1989–90 Sussex County Football League season was the 65th in the history of Sussex County Football League a football competition in England.[1] [2]
| Competition: | Sussex County Football League Division One |
| Season: | 1989–90 |
| Winners: | Wick |
| Relegated: | Lancing Redhill |
| Matches: | 306 |
| Total Goals: | 911 |
| Prevseason: | 1988–89 |
| Nextseason: | 1990–91 |
Division One featured 16 clubs which competed in the division last season, along with two new clubs, promoted from Division Two:
Also, Haywards Heath changed name to Haywards Heath Town.
| Competition: | Sussex County Football League Division Two |
| Season: | 1989–90 |
| Winners: | Bexhill Town |
| Promoted: | Bexhill Town Oakwood |
| Relegated: | Ferring Storrington |
| Matches: | 240 |
| Total Goals: | 741 |
| Prevseason: | 1988–89 |
| Nextseason: | 1990–91 |
Division Two featured eleven clubs which competed in the division last season, along with five new clubs.
| Competition: | Sussex County Football League Division Three |
| Season: | 1989–90 |
| Winners: | Worthing United |
| Promoted: | Worthing United Sidley United |
| Matches: | 182 |
| Total Goals: | 607 |
| Prevseason: | 1988–89 |
| Nextseason: | 1990–91 |
Division Three featured ten clubs which competed in the division last season, along with four new clubs:
Also, Falcons changed name to Rottingdean.