| Competition: | Ljubljana Subassociation League |
| Season: | 1939–40 |
| Winners: | Železničar Maribor |
| Prevseason: | 1938–39 |
| Nextseason: | 1940–41 |
The 1939–40 Ljubljana Subassociation League was the 21st season of the Ljubljana Subassociation League. Železničar Maribor won the league for the second time, defeating I. SSK Maribor in the final.[1]