Karlsdorf-Neuthard is a municipality in the district of Karlsruhe in Baden-Württemberg, Germany.

The municipality of Karlsdorf-Neuthard was formed by a voluntary merger of the villages of Karlsdorf and Neuthard on January 1, 1975.

Karlsdorf was founded in 1813, when Dettenheim residents, who frequently experienced floods from the river Rhine, resettled on approval of Karl, Grand Duke of Baden within the confines of Altenbürg.

The village belonged to the Bishopric of Speyer and was assigned to the Grand Duchy of Baden in 1803.

Population development:[3] Karlsdorf-Neuthard is twinned with Nyergesújfalu in Hungary.