Spencer Township is one of eleven townships in Jennings County, Indiana, United States. As of the 2020 census, its population was 2,416 (up from 2,326 at 2010) and it contained 938 housing units.
According to the 2010 census, the township has a total area of , of which (or 99.35%) is land and (or 0.65%) is water. The streams of Indian Creek, Little Mutton Creek, Powder Creek, Storm Creek, Tea Creek and Twomile Creek run through this township.
The township contains eight cemeteries: Barkman, Hunt, Myers, Saint Catherines, Saint James, Sixmile, Whitcomb and Wohrer.