Denton County is located in the U.S. state of Texas. As of the 2010 census, its population was 662,614, making it the 9th-most populous county in Texas. The county seat is Denton. The 2019 Census Bureau estimate for Denton County's population is 887,207. The county, which was named for John B. Denton, was established in 1846. Denton County constitutes part of the Dallas–Fort Worth metroplex. In 2007, it was one of the fastest-growing counties in the United States.