Oak Lawn is a village in Cook County, Illinois, United States. The population was 58,362 at the 2020 census. Oak Lawn is a suburb of Chicago, located southwest of the city. It shares borders with the city in two areas but is surrounded mostly by other suburbs.

Cook County is the most populous county in the U.S. state of Illinois and the second-most-populous county in the United States, after Los Angeles County, California. More than 40 percent of all residents of Illinois live within Cook County. As of 2020, the population was 5,275,541. The county seat is Chicago, the most populous city in Illinois and the third most populous city in the United States. The county is at the center of the Chicago metropolitan area.