1. Fußballclub Union Berlin e. V., commonly known as Union Berlin (pronounced [ˈeːɐ̯stɐ ʔɛfˈt͡seː ʔuˈni̯oːn bɛʁˈliːn] ), is a professional German football club based in Berlin.
The club’s origins can be traced to 1906, when its predecessor FC Olympia Oberschöneweide was founded. During the Cold War, Union was based in East Berlin, joining the German league structure upon the reunification of the country in 1990. From 2009 until 2019, they competed in the 2. Bundesliga, the second tier of German football. In 2019, Union won promotion to the Bundesliga for the first time in the club’s history. In 2021, Union finished seventh in the league to qualify to the inaugural UEFA Europa Conference League. In 2022, the club qualified for the UEFA Europa League by finishing fifth. The following season, the club qualified for the Champions League for the first time in their history, by finishing fourth in the Bundesliga.
The home ground of the club is the Stadion An der Alten Försterei. It is the second-largest in the German capital and has been home to Union Berlin and its forerunners since it opened in 1920. The stadium also hosts concerts and the annual Weihnachtssingen Christmas carols event.
As of 30 June 2026, Union Berlin has 72,172 official members. The club has become well known for its enthusiastic and creative fan base and its chant “Eisern Union” (Iron Union).