1. FC Köln was formed in 1948 through the merger of Kölner BC 01 and SpVgg Sülz 07, two successful local sides. It was a founding member of the Bundesliga in 1963 and was crowned its inaugural champions the following year. The club enjoyed golden eras in the 1960s and 1980s, winning three national championships and four DFB-Pokal titles; this includes the inaugural Bundesliga and a domestic double in 1978. After a decline beginning in the 1990s, Köln became known as yo-yo club due to frequent promotions and relegations between the top two tiers. A resurgence in the 2010s brought European qualification and financial stability, but recent seasons have been marked by relegation struggles.

The club is nicknamed Die Geißböcke (The Billy Goats) in reference to its mascot, a male goat named Hennes after veteran Köln player and manager Hennes Weisweiler. The first Hennes was donated by a circus entrepreneur as a Cologne carnival joke. The current mascot is Hennes IX as of 1 August 2019 after Hennes VIII was retired by the club due to old age. Another nickname for the club, more common locally due to its ambiguity, is FC, a common German abbreviation for football clubs. Characteristic for the dialect spoken around Cologne, this is pronounced "EF-tsay", in contrast to the Standard German pronunciation of the abbreviation where the second syllable is emphasized.