Charter Oak Township is a township in Crawford County, Iowa, United States.

Charter Oak Township covers an area of 35.71 square miles (92.5 km2) and contains one incorporated settlement, Charter Oak.

According to the USGS, it contains four cemeteries: Charter Oak, Saint Boniface, Saint John and Saint Paul.

The stream of Emigrant Creek runs through this township.

This article about the geography of Crawford County, Iowa is a stub.