Gmina Kotlin is a rural gmina (administrative district) in Jarocin County, Greater Poland Voivodeship, in west-central Poland. Its seat is the village of Kotlin, which lies approximately 13 kilometres (8 mi) south-east of Jarocin and 74 km (46 mi) south-east of the regional capital Poznań.
The gmina covers an area of 84.08 square kilometres (32.5 sq mi), and as of 2006 its total population is 7,124.
Gmina Kotlin contains the villages and settlements of Kotlin, Kurcew, Magnuszewice, Orpiszewek, Parzew, Racendów, Sławoszew, Twardów, Wilcza, Wola Książęca, Wysogotówek and Wyszki.
Gmina Kotlin is bordered by the gminas of Czermin, Dobrzyca, Jarocin, Pleszew and Żerków.