Gmina Wąsosz is a rural gmina (administrative district) in Grajewo County, Podlaskie Voivodeship, in north-eastern Poland. Its seat is the village of Wąsosz, which lies approximately 17 kilometres (11 mi) south-west of Grajewo and 73 km (45 mi) north-west of the regional capital Białystok.

The gmina covers an area of 117.92 square kilometres (45.5 sq mi), and as of 2006 its total population is 3,999 (3,954 in 2011).

Gmina Wąsosz contains the villages and settlements of Bagienice, Bukowo Duże, Jaki, Kędziorowo, Kolonia-Gródź, Kolonia-Łazy, Kolonie-Ławsk, Komosewo, Kudłaczewo, Ławsk, Łempice, Modzele, Niebrzydy, Nieciki, Sulewo-Kownaty, Sulewo-Prusy, Szymany, Wąsosz, Zalesie and Żebry.

Gmina Wąsosz is bordered by the gminas of Grabowo, Grajewo, Przytuły, Radziłów and Szczuczyn.

• Polish official population figures 2006