Magnolia Township is located in Putnam County, Illinois. As of the 2010 census, its population was 1,066 and it contained 532 housing units.
According to the 2010 census, the township has a total area of , of which (or 97.37%) is land and (or 2.60%) is water. The village of McNabb is located in the north of the township and the village of Magnolia is located in its south.