Centralia is a city in Boone County in the U.S. state of Missouri. The population was 4,541 at the 2020 census, with an estimated population of 4,244 in 2018. A very small portion of the city lies in Audrain County.

Boone County is located in the U.S. state of Missouri. Centrally located in Mid-Missouri, its county seat is Columbia, Missouri's fourth-largest city and location of the University of Missouri. As of the 2020 census, the population was 183,610, making it the state's eighth-most populous county. The county was organized November 16, 1820, and named for the then recently deceased Daniel Boone, whose kin largely populated the Boonslick area, having arrived in the 1810s on the Boone's Lick Road. Boone County comprises the Columbia Metropolitan Area. The towns of Ashland and Centralia are the second and third most populous towns in the county.