| Official Name: | Washington Township, Buena Vista County |
| Settlement Type: | Township |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Type2: | County |
| Subdivision Name2: | Buena Vista |
| Area Total Km2: | 90.17 |
| Area Land Km2: | 90.12 |
| Area Water Km2: | 0.05 |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 34.81 |
| Area Land Sq Mi: | 34.79 |
| Area Water Sq Mi: | 0.02 |
| Population As Of: | 2000 |
| Population Total: | 663 |
| Population Density Km2: | 7.4 |
| Population Density Sq Mi: | 19.1 |
| Elevation Footnotes: | [1] |
| Elevation M: | 427 |
| Elevation Ft: | 1401 |
| Coordinates: | 42.6983°N -95.2056°W |
| Blank Name: | FIPS code |
| Blank Info: | 19-94461[2] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 0468905 |
Washington Township is one of eighteen townships in Buena Vista County, Iowa, United States. As of the 2000 census, its population was 663.
Washington Township covers an area of 34.81sqmi and contains one incorporated settlement, Truesdale. According to the USGS, it contains one cemetery, Buena Vista Memorial Park.