Zielonka [ʑɛˈlɔŋka] is a village in the administrative district of Gmina Sośno, within Sępólno County, Kuyavian-Pomeranian Voivodeship, in north-central Poland. It lies approximately 3 kilometres (2 mi) north-east of Sośno, 14 km (9 mi) south-east of Sępólno Krajeńskie, and 37 km (23 mi) north-west of Bydgoszcz.