The municipality of Heirefos was established on 1 January 1838 (see formannskapsdistrikt law). In 1900, 610 people lived in the municipality on 67 different farms. During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1967, Herefoss (population: 585) was merged with the neighboring municipalities of Birkenes (population: 1,883) and Vegusdal (population: 582), forming the new municipality of Birkenes with its administrative centre located at Birkeland.[3]
The municipality (originally the parish) is named after the old Herefoss farm (Old Norse: Hegrafors) since the first Herefoss Church was built there. The first element is the name of the local river, Hegra. This name is derived from the word hegri which means "heron", likely the grey heron which inhabits the area. The last element is fors which means "waterfall".[4] Historically, the name of the municipality was spelled Hegrefoss. On 3 November 1917, a royal resolution changed the spelling of the name of the municipality to Herefoss.[5]
The municipal council (herredsstyre) of Herefoss was made up of 13 representatives that were elected to four-year terms. The tables below show the historical composition of the council by political party.