Gmina Wierzbno is a rural gmina (administrative district) in Węgrów County, Masovian Voivodeship, in east-central Poland. Its seat is the village of Wierzbno, which lies approximately 15 kilometres (9 mi) south-west of Węgrów and 58 km (36 mi) north-east of Warsaw.
The gmina covers an area of 103.09 square kilometres (39.8 sq mi), and as of 2006 its total population is 3,100 (2,930 in 2013).
Gmina Wierzbno contains the villages and settlements of Adamów, Brzeźnik, Cierpięta, Czerwonka, Czerwonka-Folwark, Filipy, Helenów, Janówek, Jaworek, Józefy, Karczewiec, Kazimierzów, Koszewnica, Krypy, Las Jaworski, Majdan, Nadzieja, Natolin, Orzechów, Ossówno, Rąbież, Skarżyn, Soboń, Stary Dwór, Strupiechów, Sulki, Świdno, Wąsosze, Wierzbno, Wólka, Wyczółki and Wyględówek.
Gmina Wierzbno is bordered by the gminas of Dobre, Grębków, Kałuszyn, Korytnica and Liw.