Mundelein is a village in Lake County, Illinois, United States and a northern suburb of Chicago. Per the 2020 census, the population was 31,560, making this the fourth largest town in Lake County. The village straddles Libertyville Township and Fremont Township, and borders Grayslake, Ivanhoe, Diamond Lake, and Libertyville. The village lies 33 miles northwest of the Chicago Loop.