| Official Name: | Decker Township |
| Settlement Type: | Township |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Indiana |
| Subdivision Type2: | County |
| Subdivision Name2: | Knox |
| Subdivision Type3: | Township Seat |
| Subdivision Name3: | Decker |
| Subdivision Type5: | School District |
| Subdivision Name5: | South Knox School Corporation |
| Government Type: | Indiana township |
| Area Total Sq Mi: | 46.43 |
| Area Land Sq Mi: | 44.35 |
| Area Water Sq Mi: | 2.08 |
| Population As Of: | 2020 |
| Population Total: | 209 |
| Population Density Sq Mi: | auto |
| Elevation Footnotes: | [1] |
| Elevation M: | 122 |
| Elevation Ft: | 400 |
| Coordinates: | 38.4756°N -87.6333°W |
| Blank Name: | FIPS code |
| Blank Info: | 18-17128[2] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 453256 |
Decker Township is one of ten townships in Knox County, Indiana. As of the 2020 census, its population was 209 (down from 227 at 2010[3]) and it contained 95 housing units.[4]
Decker Township is named for the Decker family of pioneer settlers.[5]
According to the 2010 census, the township has a total area of, of which (or 95.52%) is land and (or 4.48%) is water.[3]