The 1990–91 season was the 49th in the history of Eastern Counties Football League a football competition in England.[1]
Wisbech Town were champions, winning their third Eastern Counties Football League title, while Braintree Town were promoted to the Southern Football League for the first time in their history.
| Competition: | Eastern Counties Football League Premier Division |
| Season: | 1990–91 |
| Winners: | Wisbech Town |
| Promoted: | Braintree Town |
| Matches: | 420 |
| Total Goals: | 1293 |
| Prevseason: | 1989–90 |
| Nextseason: | 1991–92 |
The Premier Division featured 20 clubs which competed in the division last season, along with one new club, promoted from Division One:
| Competition: | Eastern Counties Football League Division One |
| Season: | 1990–91 |
| Winners: | Norwich United |
| Promoted: | Norwich United Brightlingsea United |
| Matches: | 342 |
| Total Goals: | 1076 |
| Prevseason: | 1989–90 |
| Nextseason: | 1991–92 |
Division One featured 16 clubs which competed in the division last season, along with three new clubs:
Also, Coalite Yaxley changed name to Clarksteel Yaxley.