The 1920–21 Northern Football League season was the 28th in the history of the Northern Football League, a football competition in Northern England.
| Competition: | Northern League |
| Season: | 1920–21 |
| Winners: | Bishop Auckland |
| Matches: | 182 |
| Total Goals: | 645 |
| Prevseason: | 1919–20 |
| Nextseason: | 1921–22 |
The league featured 12 clubs which competed in the last season, along with two new clubs: