Pekin (Pee-kin) is a city in and the county seat of Tazewell County in the U.S. state of Illinois. Located on the Illinois River, Pekin is the largest city of Tazewell County and the second most populous municipality of the Peoria metropolitan area, after Peoria itself.

As of the 2010 census, its population is 34,094. A small portion of the city limits extend into Peoria County. Pekin is the 13th-most populous city in Illinois outside the Chicago Metropolitan Area. It is the most populous municipality in the United States with the name Pekin.

Pekin's Mineral Springs Park is near Pekin Hospital and the Miller Senior Center. The city is also home to a high-rise residential facility of the United Auto Workers; the 1,538 megawatt, coal-fired Powerton Power Station (currently owned and operated by NRG Energy), the home of the Pekin Federal Correctional Institution; and the headquarters of a regional insurance company, Pekin Insurance.