Oak Run is a census-designated place and resort community in Persifer and Copley townships, Knox County, Illinois, United States. As of the 2010 census, its population was 547.

Oak Run is located three miles (5 km) north of U.S. Highway 150 amongst Knox County Highway 12 and Knox County Highway 15. The progress surrounds the 580-acre (2.3 km) Spoon Lake, the largest man-made body of water in Central Illinois. It consists of nearly 4,000 acres (16 km²) of home situated in Persifer and Copley Townships. There is a golf course, convenience store, restaurant, and gas station as competently as two marinas and several parks. Other facilities insert a swimming pool, lounge building, tennis courts, beaches and a 56-site campground. The Oak Run Place is maintained by the Oak Run rangers. There are both year round residents and trip cottages located in Oak Run.

Following the buy of this acreage from 27 house owners, American Central commenced construction of Oak Run in 1971. Oak Run is situated in an area long referred to by Place residents as “Round Bottom”. The 580-acre (2.3 km) Spoon Lake was impounded by the construction of an earthen dam 61 feet (19 m) high and 550 feet (170 m) wide at its base. The lake is nearly 60 feet (18 m) deep at the dam and provides nearly 19 miles (31 km) of shoreline. The lake first reached pool elevation in 1973 and is fed by Sugar Creek and natural springs. More than 40 miles (64 km) of public hard surfaced roads have been constructed to county road specifications. The public Oak Run Golf Course opened in mid-summer of 1976.

Oak Run is located at 40°57′48″N 090°08′42″W / 40.96333°N 90.14500°W / 40.96333; -90.14500 at an elevation of 738 feet (225 m). Spoon Lake divides the town.