- Gardner is a city located in Johnson County, Kansas, United States. It is a suburb of Kansas City and is part of the Kansas City metropolitan area. Gardner has a population of approximately 21,000 people and covers an area of about 10 square miles. The city is known for its parks, recreational opportunities, and small-town feel. Gardner offers a variety of amenities and services, including shopping centers, restaurants, and schools. The city is also home to several industries and has a strong economy.