Karnkowo [karnˈkɔvɔ] is a village in the administrative district of Gmina Czerwińsk nad Wisłą, within Płońsk County, Masovian Voivodeship, in east-central Poland. It lies approximately 14 kilometres (9 mi) north-east of Czerwińsk nad Wisłą, 20 km (12 mi) south of Płońsk, and 47 km (29 mi) north-west of Warsaw.