Osowiec-Twierdza [ɔˈsɔvjɛt͡s] is a village in the administrative district of Gmina Goniądz, in Mońki County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately 5 kilometres (3 mi) south of Goniądz, 11 km (7 mi) north-west of Mońki, and 51 km (32 mi) north-west of the regional capital Białystok.