Sośno was formerly part of the German Empire. In the German Empire, the place was called Sassenau.
The place is now called Sośno and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Soßnow | German Empire | Flatow | before the Versailles Treaty |
| Sośno | Poland | Sępólno | after the Versailles Treaty |
| Sassenau | German Empire | Zempelburg | 1939 |
| Sośno | Poland | Sępólno Krajeńskie | 1945 |
| Sośno | Poland | Bydgoszcz | 1992 |