Middlefield is a village in Middlefield Township, Geauga County, Ohio, United States. The population was 2,690 at the 2010 census.Middlefield is known for being the center of the world's fourth largest Amish settlement, and its significant manufacturing base, which includes Gold Key Processing, Inc., Duncan Toys and KraftMaid.Because of its central location, home of the areas' public schools and prominent business and retail presence, Middlefield village is considered the hub community for Huntsburg, Parkman, and Middlefield Townships, home to approximately 15,000 total residents.