Olathe is a city in and the county seat of Johnson County, Kansas, United States. Located in northeastern Kansas, it is also the fifth most populous city in the state. As a suburb of Kansas City, Missouri, Olathe is the fourth-largest city in the Kansas City Metropolitan Area. It is bordered by the cities of Lenexa to the north, Overland Park to the east, and Gardner to the southwest. The US Census Bureau ranked Olathe the 24th fastest-growing city in the nation.