Lillington is a town in and the county seat of Harnett County, North Carolina, United States. Its population was 3,194 at the 2010 census, and was 4,735 in the 2020 census. Lillington is a part of the Dunn micropolitan area, which is also a part of the greater Raleigh–Durham–Cary combined statistical area as defined by the United States Census Bureau.