Janczewko [janˈt͡ʂɛfkɔ] is a village in the administrative district of Gmina Jedwabne, within Łomża County, Podlaskie Voivodeship, in north-eastern Poland.^[1]

It lies approximately 3 kilometres (2 mi) south-west of Jedwabne, 18 km (11 mi) north-east of Łomża, and 62 km (39 mi) west of the regional capital Białystok.