WebWebsite. yakimawa.gov. Yakima ( / ˈjækɪmɑː / or / ˈjækɪmə /) is a city in, and the county seat of, Yakima County, Washington, United States, and the state's 11th most populous city. As of the 2020 census, the city had a total population of 96,968 and a metropolitan population of 256,728. [3]