Keller is a city in Tarrant County, Texas, United States, in the Dallas–Fort Worth metroplex. According to the 2020 census, the city's population …Keller is a city in Tarrant County, Texas, United States, in the Dallas–Fort Worth metroplex. According to the 2020 census, the city's population is 45,776, making Keller the 78th most populated city in Texas. The most recent population estimate, as of July 1, 2021, is 45,397.