Gmina Mieleszyn is a rural gmina (administrative district) in Gniezno County, Greater Poland Voivodeship, in west-central Poland. Its seat is the village of Mieleszyn, which lies approximately 17 kilometres (11 mi) north-west of Gniezno and 50 km (31 mi) north-east of the regional capital Poznań.
The gmina covers an area of 99.24 square kilometres (38.3 sq mi), and as of 2006 its total population is 3,989.