| Competition: | Welsh Football League Division One |
| Season: | 2019–20 |
| Winners: | Trefelin B.G.C. |
| Promoted: | Trefelin B.G.C., Port Talbot Town F.C. and Risca United F.C. |
| Nextseason: | 2020–21 |
The Welsh Football League Division One 2019–20 season is the final season of this football league in South Wales. It is due to be replaced by the FAW League One for 2020–21. It is Tier 3 of the Welsh League Pyramid in South Wales.
After the season was cut short by the Coronavirus-19 pandemic the FAW confirmed its promotion and relegation decision on 16 June 2020.[1]
The top 3 teams in the 2019–20 season have been promoted to the Cymru South. Which teams are due to make up the new FAW League One for the 2020–21 season are yet to be decided by the Football Association of Wales. A decision is expected in July 2020.