Due to the administration reform of 1936 Bad Rappenau turned into the district of Sinsheim. On April 1, 1950, the village Zimmerhof has been incorporated into the municipality. From 1971 to 1973 eight further municipalities had been incorporated into Bad Rappenau. Due to the district reform of January 1, 1973, Bad Rappenau turned into the district of Heilbronn. This district belongs to the administrative district of Stuttgart, so a municipality previously belonging to Baden is now administrated by Württemberg. Also in 1973 the municipality got town rights. On January 1, 2003, Bad Rappenau became a "Große Kreisstadt".