Middleton is a city in Canyon County, Idaho, United States. The population amounted to 9,091 at the 2021 census estimate, up from 5,524 at the 2010 census and 2,978 in 2000. It is part of the Boise City–Nampa, Idaho Metropolitan Statistical Area.

Canyon County is located in the U.S. state of Idaho. As of the 2020 Census, the population was 231,105, which by 2022 was estimated to have risen to 251,065. making it the second-most populous county in Idaho. The county seat is Caldwell, and its largest city is Nampa. Canyon County is part of the Boise metropolitan area.