Sebastianowo [sɛbastjaˈnɔvɔ] is a village in the administrative district of Gmina Książ Wielkopolski, within Śrem County, Greater Poland Voivodeship, in west-central Poland. It lies approximately 4 kilometres (2 mi) south of Książ Wielkopolski, 17 km (11 mi) east of Śrem, and 47 km (29 mi) south-east of the regional capital Poznań.