| Official Name: | Walnut Township |
| Settlement Type: | Township |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Type2: | County |
| Subdivision Name2: | Marshall |
| Government Type: | Indiana township |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 37.75 |
| Area Land Sq Mi: | 37.71 |
| Area Water Sq Mi: | 0.04 |
| Area Water Percent: | 0.11 |
| Population As Of: | 2020 |
| Population Footnotes: | [1] |
| Population Total: | 2873 |
| Population Density Sq Mi: | 72.8 |
| Elevation M: | 249 |
| Elevation Ft: | 817 |
| Coordinates: | 41.2253°N -86.2069°W |
| Postal Code Type: | ZIP codes |
| Postal Code: | 46501, 46504, 46563, 46570 |
| Blank Name: | GNIS feature ID |
| Blank Info: | 0453970 |
Walnut Township is one of ten townships in Marshall County, Indiana, United States. As of the 2020 census, its population was 2,873 (up from 2,747 at 2010[2]) and it contained 1,140 housing units.
Walnut Township was organized in 1859.[3]
The Argos Izaak Walton League Historic District was listed on the National Register of Historic Places in 2011.[4]
According to the 2010 census, the township has a total area of, of which (or 99.89%) is land and (or 0.11%) is water.[2]
The township contains these two cemeteries: Maple Grove and McGrew.
Walnut Township residents may obtain a free library card from the Argos Public Library in Argos.[5]