Olszewko [ɔlˈʂɛfkɔ] is a village in the administrative district of Gmina Kuczbork-Osada, within Żuromin County, Masovian Voivodeship, in east-central Poland. It lies approximately 4 kilometres (2 mi) south of Kuczbork-Osada, 10 km (6 mi) east of Żuromin, and 114 km (71 mi) north-west of Warsaw.