The 1989–90 season was the 48th in the history of Eastern Counties Football League a football competition in England.[1]
Sudbury Town were champions for the second time in a row, winning their seventh Eastern Counties Football League title and were promoted to the Southern Football League for the first time in their history.
| Competition: | Eastern Counties Football League Premier Division |
| Season: | 1989–90 |
| Winners: | Sudbury Town |
| Promoted: | Sudbury Town |
| Matches: | 420 |
| Total Goals: | 1447 |
| Prevseason: | 1988–89 |
| Nextseason: | 1990–91 |
The Premier Division featured 19 clubs which competed in the division last season, along with two new clubs, promoted from Division One:
| Competition: | Eastern Counties Football League Division One |
| Season: | 1989–90 |
| Winners: | Cornard United |
| Promoted: | Cornard United |
| Matches: | 272 |
| Total Goals: | 887 |
| Prevseason: | 1988–89 |
| Nextseason: | 1990–91 |
Division One featured twelve clubs which competed in the division last season, along with five new clubs:
Also, Loadwell Ipswich changed name to Ipswich Wanderers.