Grabniak [ˈɡrabɲak] is a village in the administrative district of Gmina Sobolew, within Garwolin County, Masovian Voivodeship, in east-central Poland. It lies approximately 4 kilometres (2 mi) south-east of Sobolew, 22 km (14 mi) south of Garwolin, and 74 km (46 mi) south-east of Warsaw.