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