The 1990–91 United Counties League season was the 84th in the history of the United Counties League, a football competition in England.
| Competition: | United Counties League Premier Division |
| Season: | 1990–91 |
| Winners: | Bourne Town |
| Relegated: | Burton Park Wanderers |
| Matches: | 462 |
| Total Goals: | 1380 |
| Prevseason: | 1989–90 |
| Nextseason: | 1991–92 |
The Premier Division featured 22 clubs which competed in the division last season, no new clubs joined the division this season.
| Competition: | United Counties League Division One |
| Season: | 1990–91 |
| Winners: | Daventry Town |
| Promoted: | Daventry Town |
| Matches: | 342 |
| Total Goals: | 1125 |
| Prevseason: | 1989–90 |
| Nextseason: | 1991–92 |
Division One featured 18 clubs which competed in the division last season, along with one new club:
Also, Irchester Eastfield changed name to Irchester United.