Piastowo [pjasˈtɔvɔ] is a village in the administrative district of Gmina Gąsawa, within Żnin County, Kuyavian-Pomeranian Voivodeship, in north-central Poland. It lies approximately 7 kilometres (4 mi) east of Gąsawa, 13 km (8 mi) south-east of Żnin, and 39 km (24 mi) south of Bydgoszcz.