| Competition: | Ljubljana Subassociation League |
| Season: | 1920–21 |
| Winners: | Ilirija |
| Prevseason: | 1920 |
| Nextseason: | 1921–22 |
The 1920–21 Ljubljana Subassociation League was the second season of the Ljubljana Subassociation League. The league was separated into Celje, Ljubljana and Maribor subdivisions.[1] The final was played between the previous season winners Ilirija from Ljubljana, and Athletik from Celje. Ilirija defeated Athletik in the final and won their second title in a row.[1]