League City, Texas. From Wikipedia, the free encyclopedia. League City is a city in the U.S. state of Texas, within Houston–The Woodlands–Sugar Land metropolitan area. The city is in the county of Galveston As of the 2010 census, League City's population was 83,560, up from 45,444 at the 2000 census. The city has a small portion north of Clear Creek within Harris County zoned for residential and commercial uses.