| Competition: | Cymru Alliance |
| Season: | 1999–2000 |
| Winners: | Oswestry Town |
| Relegated: | Corwen Amateurs |
| Prevseason: | 1998–99 |
| Nextseason: | 2000–01 |
The 1999–2000 Cymru Alliance was the tenth season of the Cymru Alliance after its establishment in 1990. The league was won by Oswestry Town.