Jefferson Township is one of nine townships in Sullivan County, Indiana, United States.

At the 2020 census, its population was 355 and it contained 218 housing units.

[1] According to the 2010 census, the township has a total area of 42.95 square miles (111.2 km2), of which 42.42 square miles (109.9 km2) (or 98.77%) is land and 0.53 square miles (1.4 km2) (or 1.23%) is water.

[3] (This list is based on USGS data and may include former settlements.)

The township contains six cemeteries: Hale, McDade, Pirtle, Posey, Smith and Woodward.