Hazleton is a city in Luzerne County, Pennsylvania, United States. The population was 29,963 at the 2020 census. Hazleton is the second-m…Hazleton is a city in Luzerne County, Pennsylvania, United States. The population was 29,963 at the 2020 census. Hazleton is the second-most populous city in Luzerne County. It was incorporated as a borough on January 5, 1857, and as a city on December 4, 1891.