Hamilton County is a county in the U.S. state of Indiana. The 2020 United States Census recorded a population of 347,467. The county seat is Noblesville.

Noblesville is a city in and the county seat of Hamilton County, Indiana, United States, a part of the north Indianapolis suburbs along the White River. The population was 69,604 at the 2020 census, making it the state's 10th most populous city, up from 14th in 2010. The city is part of Delaware, Fall Creek, Noblesville, and Wayne townships.