Alabaster is a city and southern suburb of Birmingham in Shelby County, Alabama, United States. At the 2020 census, the population was 33,284. Alabaster is the 16th largest city in Alabama by a number of residents. Alabaster mostly occupies the Cahaba and Opossum valleys, which are divided by the Pine Ridge that runs north to south. The valleys are drained by small creeks (Buck Creek, Beaverdam Creek) that flow into the Cahaba River.