The 1999–2000 United Counties League season was the 93rd in the history of the United Counties League, a football competition in England.
| Competition: | United Counties League Premier Division |
| Season: | 1999–2000 |
| Winners: | Ford Sports Daventry |
| Matches: | 380 |
| Total Goals: | 1342 |
| Prevseason: | 1998–99 |
| Nextseason: | 2000–01 |
The Premier Division featured 19 clubs which competed in the division last season, along with one new club, promoted from Division One:
| Competition: | United Counties League Division One |
| Season: | 1999–2000 |
| Winners: | Cottingham |
| Matches: | 306 |
| Total Goals: | 1078 |
| Prevseason: | 1998–99 |
| Nextseason: | 2000–01 |
Division One featured 17 clubs which competed in the division last season, along with one new club: