Uścianek Wielki (Polish pronunciation: [uɕˈtɕanɛk ˈfjɛlkʲi]) is a village in the administrative district of Gmina Zaręby Kościelne, within Ostrów Mazowiecka County, Masovian Voivodeship, in east-central Poland. It lies approximately 17 km (11 mi) east of Ostrów Mazowiecka and 97 km (60 mi) north-east of Warsaw.