Blue Mound Township is located in Macon County, Illinois. As of the 2010 census, its population was 890 and it contained 387 housing units. In the 2020 census, the population had become 822 in 382 housing units.
According to the 2010 census, the township has a total area of , of which (or 99.88%) is land and (or 0.12%) is water.