| Competition: | Welsh Alliance League |
| Season: | 2002–03 |
| Winners: | Glantraeth |
| Matches: | 210 |
| Total Goals: | 824 |
| Prevseason: | 2001–02 |
| Nextseason: | 2003–04 |
The 2002–03 Welsh Alliance League is the 19th season of the Welsh Alliance League, which is in the third level of the Welsh football pyramid.
The league consists of fifteen teams and concluded with Glantraeth as champions and promoted to the Cymru Alliance.
Amlwch Town were champions in the previous season and were promoted to the Cymru Alliance. They were replaced by Denbigh Town who were relegated from the Cymru Alliance, Gwynedd League champions, Bodedern Athletic and Clwyd League champions, Sealand Leisure.
| Team | Location | Ground | |
|---|---|---|---|
| Parc Meurig | |||
| Cae Ty Cristion | |||
| Lon yr Ysgol | |||
| Y Morfa Stadium | |||
| Central Park. | |||
| Cae Ffwt | |||
| Trefdraeth | |||
| Arriva Ground | |||
| Ffordd Padarn | |||
| Penmaenmawr Phoenix | Cae Sling | ||
| Bastion Road | |||
| Dolfechlas Road | |||
| Rhyl Reserves | Belle Vue | ||
| Sealand Leisure | |||
| Y Felinheli | Cae Selio |