Berg was the main parish in a district which included Rokke and Halden until 1721. Halden subsequently became the main parish in the district. By a royal proclamation in 1769, Berg became the head of its own district with Rokke and Asak as annexes. The parish of Berg was established as a municipality on 1 January 1838 . The Østfold Line was built through Berg in 1879 and Berg Station was opened to serve it.
The name
The municipality was named after the farm Berg, since the first church was built on its ground. The name is identical with the wordberg meaning 'rocky hill; mountain'.