Kearny County is a county located in the U.S. state of Kansas. Its county seat and most populous city is Lakin. As of the 2020 census, the county population was 3,983. The county is named in honor of Philip Kearny, a general during the American Civil War that died during the Battle of Chantilly.

Philip Kearny Jr. was a United States Army officer, notable for his leadership in the Mexican–American War and American Civil War. He served in French Emperor Napoleon III's Imperial Guard at the Battle of Solferino.