The Dannebrog, named after the flag of Denmark, was built in 1931–1932 at the Naval Dockyard in Copenhagen. She replaced the previous royal vessel, an 1879 paddle steamer, also called Dannebrog. The yacht has dual functions: it is primarily the Royal Yacht during peacetime; it can become a hospital ship during emergency alerts or war.
The ship’s hull is a riveted steel construction on transverse frames. The ship has a clipper stem and an elliptic stern. Viewed from the side, the ship may be divided into two sections. In front of the funnel there is space for the crew, any cargo, and the engine. At the rear is the Royal Apartment. This could accommodate patients if ever the yacht were used as a hospital. During visits to Danish and foreign ports the covered quarterdeck is used for receptions.