Trześcianka [tʂɛɕˈt͡ɕaŋka] is a village in the administrative district of Gmina Narew, within Hajnówka County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately 6 kilometres (4 mi) north-west of Narew, 24 km (15 mi) north of Hajnówka, and 28 km (17 mi) south-east of the regional capital Białystok.

Trześcianka is mostly inhabited by Orthodox Belarusians.