Cieksyn [ˈt͡ɕɛksɨn] is a village in the administrative district of Gmina Nasielsk, within Nowy Dwór County, Masovian Voivodeship, in east-central Poland. It lies approximately 9 kilometres (6 mi) south-west of Nasielsk, 15 km (9 mi) north of Nowy Dwór Mazowiecki, and 45 km (28 mi) north-west of Warsaw.