Osielsko [ɔˈɕɛlskɔ] is a village in Bydgoszcz County, Kuyavian-Pomeranian Voivodeship, in north-central Poland.

[2] In 1155, Osielsk was mentioned in a document of Polish monarch Bolesław IV the Curly.

In 1807, it was regained by Poles and included within the short-lived Duchy of Warsaw, and after its dissolution, in 1815 it was reannexed by Prussia, and from 1871 it was part of the German Empire, within which it administratively belonged to Kreis Bromberg in the Province of West Prussia.

[3] Local Poles were also murdered by the German Einsatzkommando 16 near Otorowo, also as part of the Intelligenzaktion.

[4] The most notable local sports club is baseball team Dęby Osielsko [pl].