Lacon Township is located in Marshall County, Illinois, USA. As of the 2010 census, its population was 2,501 and it contained 1,116 housing units.
Lacon Township takes its name from Laconia, a region of Greece.
According to the 2010 census, the township has a total area of , of which (or 78.81%) is land and (or 21.19%) is water.