Zielony Gaj (Polish pronunciation: [ʑɛˈlɔnɨ ˈɡaj]) is a village in the administrative district of Gmina Janów, within Sokółka County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately 7 kilometres (4 mi) north-east of Janów, 21 km (13 mi) north-west of Sokółka, and 46 km (29 mi) north of the regional capital Białystok.