Czarnocin [t͡ʂarˈnɔt͡ɕin] is a village in the administrative district of Gmina Piątnica, within Łomża County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately 3 kilometres (2 mi) north of Piątnica, 6 km (4 mi) north of Łomża, and 74 km (46 mi) west of the regional capital Białystok.