FC Rastatt 04 is a German association football club from the city of Rastatt, Baden-Württemberg. It was established as Fußball-Klub Rastatt on 9 October 1904 at the Gasthaus zur Linde. A 1919 union with Fußball-Club Phoenix created Rastatt Fußballverein 04, which merged with Frankonia 1912 Rastatt on 23 August 1939 to form FC Rastatt 04. The club enjoyed its greatest success in the 1930s, 1940s, and early 1950s when it took part in top-flight regional competition in southwestern Germany.
FV won promotion to the senior regional circuit, the Bezirksliga Württemberg/Baden, in 1928, where they finished as vice champions in 1932. Their performance slipped the following season, and as a result, they failed to qualify for play in the Gauliga Baden, one of 16 new regional top-flight divisions formed in the reorganization of German football in 1933. They made single season appearances in Gauliga play in 1936 and 1939 (now playing as FC). They were also part of that league from 1941–44, until it was reduced to a rump circuit in 1944–45 when the region fell to advancing Allied forces in the latter stages of World War II.
Following the conflict, occupying Allied authorities disbanded organizations across the country, including football and sports clubs, as part of the process of denazification. The club was reestablished in 1946 as SV Fortuna Rastatt and reclaimed its traditional identity as FC Rastatt 04 on 20 January 1950. As Fortuna, the team captured the Landesliga Südbaden title in 1946 and advanced to the first division Oberliga Südwest/Süd where they won the title in 1948. Through league restructuring at the end of the 1949–50 season, the Oberliga Südwest/Nord continued as the Oberliga Südwest, while the Oberliga Südwest/Süd was integrated into the Oberliga Süd. FC's eighth-place finish in that campaign was not good enough to qualify the side for continued Oberliga play and they slipped into the Amateurliga Südbaden (II).