Tomball, Texas. Tomball (/ˈtɒmbɔːl/ TOM-bawl) is a city in Harris County in the U.S. state of Texas, a part of the Houston metropolitan area. The population was 10,753 at the 2010 census. In 1907, the community of Peck was renamed Tomball for local congressman Thomas Henry Ball, who had a major role in the development of the Port of Houston.