McLennan County is a county located on the Edwards Plateau in Central Texas. As of the 2020 census, its population was 260,579 . Its county seat and largest city is Waco. The U.S. census 2021 county population estimate is 263,115. The county is named for Neil McLennan, an early Scottish settler who worked to push back the Indians in early Texas. McLennan County is included in the Waco Metropolitan Statistical Area.