Gmina Korytnica is a rural gmina (administrative district) in Węgrów County, Masovian Voivodeship, in east-central Poland. Its seat is the village of Korytnica, which lies approximately 11 kilometres (7 mi) west of Węgrów and 60 km (37 mi) north-east of Warsaw.
The gmina covers an area of 180.54 square kilometres (69.7 sq mi), and as of 2006 its total population was 6,745 (6,464 in 2013).