Peoria is a city in Peoria County, Illinois, United States, and its county seat. Located on the Illinois River, the city had a population of 113,150 as of the 2020 census, making it the eighth-most populous city in Illinois. It is the principal city of the Peoria metropolitan area in Central Illinois, consisting of Fulton, Marshall, Peoria, Stark, Tazewell, and Woodford counties and had a combined population of 402,391 in 2020.