Williamsfield is a village in Knox County, Illinois, United States.

Illinois Route 180 runs through the east side of the village, leading north 18 miles (29 km) to Galva and south 1.5 miles (2.4 km) to U.S. Route 150.

According to the 2010 census, Williamsfield has a total area of 1.27 square miles (3.29 km2), all land.

There were 255 housing units at an average density of 200.7 per square mile (77.5/km2).

28.2% of all households were made up of individuals, and 16.4% had someone living alone who was 65 years of age or older.