Hamilton is a city in and the county seat of Marion County, Alabama, United States. It incorporated in 1896 and since 1980 has been the c…Hamilton is a city in and the county seat of Marion County, Alabama, United States. It incorporated in 1896 and since 1980 has been the county's largest city, surpassing Winfield. It was previously the largest town in 1910. At the 2020 census, the population was 7,042.