Łęg-Osiek was formerly part of the German Empire. In the German Empire, the place was called Lengden.
The place is now called Łęg-Osiek and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Leg Osiek | Russian Empire | Lipno | 1914 |
| Łęg-Osiek | Poland | Lipno | after the Versailles Treaty |
| Lengden | German Empire | Leipe (Westpr.) | 1939 |
| Łęg-Osiek | Poland | Toruń | 1945 |
| Łęg-Osiek | Poland | Toruń | 1992 |