Lake County is a county located in the U.S. state of Ohio. As of the 2010 census, the population was 230,041. The county seat is Painesville. The county was established on March 6, 1840, from land given by Cuyahoga and Geauga Counties. Its name is derived from its location on the southern shore of Lake Erie. The county borders Lake Erie to the north, Ashtabula County to the east, Geauga County to the south, and Cuyahoga County to the west.
Lake County is part of the Cleveland-Elyria, OH Metropolitan Statistical Area.