Grayslake is a village in Lake County, Illinois, United States. The village's population at the 2020 census was 21,248. It is located in the Chicago metropolitan area, about 40 miles north of Chicago's downtown, 14 miles west of Lake Michigan, and 15 miles south of the Wisconsin border. Grayslake is home to the College of Lake County, Grayslake North High School, Grayslake Central High School, the University Center of Lake County and the Lake County Fairgrounds.