After the commissioning, Admiral Hipper sailed to Baltic Sea to conduct training maneuvers. She made port calls to several Baltic ports including Estonia and Sweden. At the outbreak of World War II in September 1939, Hipper was briefly used to patrol the Baltic, but she did not see combat, and was quickly returned to training exercises and later refit in Hamburg for replacement of the straight stem with a clipper bow and the installation of the funnel cap. On 17 February 1940, the Kriegsmarine pronounced the ship fully operational, and on the following day, Admiral Hipper began her first major wartime patrol.
Hipper joined the battleships Scharnhorst and Gneisenau and the destroyers Karl Galster and Wilhelm Heidkamp in a sortie into the North Sea off Bergen, Norway. The ships attempted to locate British merchant shipping, but failed and returned to port on 20 February.
Norway coast encounter
Following her return from the North Sea sortie, Admiral Hipper was assigned as a lead ship of 2nd Group to the forces tasked with the invasion of Norway, codenamed Operation Weserübung. While steaming off the Norwegian coast, Admiral Hipper was ordered to assist the destroyer Bernd von Arnim, which fallen of the group and encountered the British destroyer HMS Glowworm. Destroyers engaged each other and Hipper was closing the distance in the meantime. Once Hipper got inside a range of fire, she started to fire salvo after salvo, scoring several hits on British destroyer. Glowworm attempted to flee, but when it became apparent she could not break away from the pursuing cruiser, she turned toward Admiral Hipper and fired a spread of torpedoes, all of which missed. The British destroyer scored one hit on Admiral Hipper’s starboard bow before a rudder malfunction set the ship on a collision course with the German cruiser.
40-meter (130 ft) section of Admiral Hipper’s armored belt on the starboard side was torn after the unavoidable collision, which caused minor flooding, but Hipper was able to resume to her mission. Glowworm on the other hand, sunk shortly after collision, as her boilers exploded leaving behind only 40 survivors who were boarded to Hipper.
Hipper arrived in Trondheim, successfully pretending to be a British warship, debarking the troops and conquering coastal batteries. Then Hipper sailed back to Germany for the repairs. After the repairs, ship was assigned to another conquest mission together the battleships Scharnhorst and Gneisenau, and four destroyers to seize Harstad in early June 1940. Once ships arrived to Harstad, allies already abandoned the port and conquest went smoothly. Group then unsuccessfully attempted to hunt down the allied convoy after which it returned to Trondheim for refuel.
On 25 July, Admiral Hipper steamed out on a commerce raiding patrol in the area between Spitzbergen and Tromsø and encountered the Finnish freighter Ester Thorden, which was found to be carrying 1.75 tons of gold. The ship was seized and sent to occupied Norway with a prize crew.