Walnut Township is a township in Barton County, Kansas, United States. As of the 2010 census, its population was 403.
Walnut Township was organized in 1876.
Walnut Township (T18S R15W) covers an area of and contains two incorporated settlements: Albert and Olmitz. According to the USGS, it contains one cemetery, Saint Anthony.
The streams of Boot Creek and Dry Creek run through this township.