Kupientyn [kuˈpjɛntɨn] is a village in the administrative district of Gmina Sabnie, within Sokołów County, Masovian Voivodeship, in east-central Poland. It lies approximately 8 kilometres (5 mi) south of Sabnie, 6 km (4 mi) north of Sokołów Podlaski, and 90 km (56 mi) east of Warsaw.