| Osiek-Włostybory | |
| Settlement Type: | Village |
| Subdivision Type: | Country |
| Subdivision Type1: | Voivodeship |
| Subdivision Name1: | Masovian |
| Subdivision Type2: | County |
| Subdivision Name2: | Sierpc |
| Subdivision Type3: | Gmina |
| Subdivision Name3: | Zawidz |
| Coordinates: | 52.8097°N 19.9531°W |
| Pushpin Map: | Poland |
Osiek-Włostybory is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.[1]