Its seat is the village of Osielsko, which lies approximately 9 kilometres (6 mi) north-east of Bydgoszcz.

The gmina covers an area of 102.89 square kilometres (39.7 sq mi), and as of 2014 its total population is 12,239.

[1] Osielsko is the richest gmina in Kuyavian-Pomeranian Voivodeship.

[2] Osielsko's main source of wealth is personal income tax paid by inhabitants of this gmina.

[3] Gmina Osielsko contains the villages and settlements of Bożenkowo, Czarnówczyn, Jagodowo, Jarużyn, Jarużyn-Kolonia, Maksymilianowo, Myślęcinek, Niemcz, Niwy, Osielsko, Strzelce Leśne, Wilcze and Żołędowo.