The Berlin outer ring is a 125 km (78 mi) long double track electrified railway, originally built by the German Democratic Republic to bypass West Berlin in preparation for the building of the Berlin Wall during the division of Germany. It was developed by East Germany for economic, transport policy, and military reasons between 1951 and 1961 and included parts of some older lines.

The Berlin Outer Freight Ring was a planned ring railway around the city of Berlin, Germany. The first sections of a line to the west of the city were built in the early 20th century as part of the Brandenburg Bypass Railway (Umgehungsbahn). Even then, there were plans for a bypass south of Berlin. The first bits were built in the early 1920 and more sections followed in the 1930s. The line could not be completed due to the impact of the Second World War. The completed section consisted of a mainly single-track link running from Teltow to Berlin-Karow to the south and east of Berlin. Part of the route line later became part of the Berlin outer ring.