On 13 February 1948, Köln formed from the merger of two other clubs. They went on to become the first Bundesliga champions.
The two previous clubs were Kölner BC, founded in 1901, and Spielvereinigung 1907 Köln-Sülz, founded in 1907. Their merger came about as a result of the reorganization of German football under the Third Reich and the re-establishment of league play after the end of World War II.
Initially assigned to the regional Oberliga West, they were one of sixteen teams chosen for the new national Bundesliga, which started play in the fall of 1963. Spurred by the goal-scoring duo of Karl-Heinz Thielen (16 goals) and Christian Müller (15), they finished at the top of the table, six points clear of runners-up Meidericher SV.
They won the league again in 1964, with second-place finishes in 1963 and 1965, then won it for a third time in 1978. After finishing as runners-up a few more times, including 1989 and 1990, they went into a slump that ended in relegation in 1998.
Since then, they have moved between the top two divisions and currently play in the second tier after being relegated in 2012.