New Castle is a home rule-class city in Henry County, Kentucky, United States. It is the seat of its county. As of the 2010 census the population was 912. African Americans attended New Castle Colored School prior to integration.

Henry County is a county located in the north central portion of the U.S. state of Kentucky bordering the Kentucky River. As of the 2020 census, the population was 15,678. Its county seat is New Castle, but its largest city is Eminence. The county was founded in 1798 from portions of Shelby County. It was named for the statesman and governor of Virginia Patrick Henry. Henry County is included in the Louisville/Jefferson County, KY-IN Metropolitan Statistical Area. Since the 1990s, it has become an increasingly important exurb, especially as land prices have become higher in neighboring Oldham County. With regard to the sale of alcohol, it is classified as a wet county.