Gmina Koźminek is a urban-rural gmina (administrative district) in Kalisz County, Greater Poland Voivodeship, in west-central Poland. Its seat is the town of Koźminek, which lies approximately 17 kilometres (11 mi) east of Kalisz and 118 km (73 mi) south-east of the regional capital Poznań.
The gmina covers an area of 88.43 square kilometres (34.1 sq mi), and as of 2006 its total population is 7,514.