| Official Name: | Washington Township, Cass County |
| Settlement Type: | Township |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Type2: | County |
| Subdivision Name2: | Cass |
| Area Total Km2: | 91.55 |
| Area Land Km2: | 91.5 |
| Area Water Km2: | 0.05 |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 35.35 |
| Area Land Sq Mi: | 35.33 |
| Area Water Sq Mi: | 0.02 |
| Population As Of: | 2000 |
| Population Total: | 310 |
| Population Density Km2: | 3.4 |
| Population Density Sq Mi: | 8.8 |
| Elevation Footnotes: | [1] |
| Elevation M: | 365 |
| Elevation Ft: | 1198 |
| Coordinates: | 41.3739°N -95.0981°W |
| Blank Name: | FIPS code |
| Blank Info: | 19-94470[2] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 0468908 |
Washington Township is one of sixteen townships in Cass County, Iowa, United States. As of the 2000 census, its population was 310.
Washington Township covers an area of 35.35sqmi and contains no incorporated settlements.