Gmina Siewierz is an urban-rural gmina (administrative district) in Będzin County, Silesian Voivodeship, in southern Poland. Its seat is the town of Siewierz, which lies approximately 18 kilometres (11 mi) north-east of Będzin and 30 km (19 mi) north-east of the regional capital Katowice.
The gmina covers an area of 115.76 square kilometres (44.7 sq mi), and as of 2019 its total population is 12,460.