Sleszynek was formerly part of the German Empire. In the German Empire, the place was called Śleszynek.
The place is now called Śleszynek and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Sleszynek | Russian Empire | Kutno | 1914 |
| Śleszynek | Poland | Kutno | 1921 |
| Śleszynek | German Empire | Kutno | 1939 |
| Śleszynek | Poland | Kutno | 1945 |
| Śleszynek | Poland | Płock | 1992 |