Kings Mills is an unincorporated community in the southwestern corner of Deerfield Township, Warren County, Ohio, United States, on the western shore of the Little Miami River. Located along I-71 twenty miles northeast of Cincinnati, it is less than a mile east of Mason, two miles southwest of South Lebanon, two and one-half miles north of Fosters, and two miles west of Hopkinsville.Another town, Gainsboro, was platted on this site in the 1820s, but it did not prosper.