Ontario Township is one of twenty-one townships in Knox County, Illinois, USA.

As of the 2010 census, its population was 943 and it contained 411 housing units.

[2] According to the 2010 census, the township has a total area of 36.26 square miles (93.9 km2), all land.

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

The township contains these two cemeteries: Oneida and Ontario.