Hamilton County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 15,039. The county seat is Webster City. The county was named to honor William W. Hamilton, a President of the Iowa State Senate.

Webster City is a city in Hamilton County, Iowa, United States. The population was 7,825 at the 2020 census. It is the county seat of Hamilton County. Webster City is known as 'Boone River Country', as the Boone River meanders along the east side of the city.