At the beginning of World War II in September, she was initially deployed to lay minefields off the German coast, but was soon transferred to the Skagerrak where she inspected neutral shipping for contraband goods.

In late 1939, Z18 Hans Lüdemann helped to laid four offensive minefields off the English coast that claimed two British destroyers and thirty-eight merchant ships.

On 30 June, Z19 Hermann Künne and her sister Z18 Hans Lüdemann were making port visits in Norway when the former accidentally rammed the pier at Moldefjord after her rudder failed.

[5] When World War II began in September, Z19 Hermann Künne was initially deployed in the German Bight where she laid defensive minefields.

[6] On the night of 17/18 October, Rear Admiral (Konteradmiral) Günther Lütjens, aboard his flagship Z21 Wilhelm Heidkamp, led Z16 Friedrich Eckoldt, Z17 Diether von Roeder, Z18 Hans Lüdemann, Z19 Hermann Künne, and Z20 Karl Galster as they laid a minefield off the mouth of the River Humber.

On the night of 12/13 November Z21 Wilhelm Heidkamp, now the flagship of the Commander of Destroyers (Führer der Zerstörer), Kapitän zur See (Captain) Friedrich Bonte, escorted Z18 Hans Lüdemann, Z19 Hermann Künne, and Z20 Karl Galster as they laid 288 magnetic mines in the Thames estuary.

[7] Less than a week later, Z21 Wilhelm Heidkamp, Z19 Hermann Künne, and Z11 Bernd von Arnim laid 180 magnetic mines in the Thames Estuary on the night of 17/18 November.

Under the command of Commodore (Kommodore) Bonte in his flagship Z19 Hermann Künne, Z4 Richard Beitzen, Z8 Bruno Heinemann, Z14 Friedrich Ihn and Z15 Erich Steinbrinck laid 240 mines off the mouth of the River Tyne, where the navigation lights were still lit.

[9] When they arrived off the Ofotfjord on the morning of 9 April, Z19 Hermann Künne landed her troops at the head of the Herjangsfjord and helped to capture the Norwegian Army barracks at Elvegårdsmoen.

When the British destroyer hit and sank Z22 Anton Schmitt with a torpedo, Z19 Hermann Künne was only 40 meters (44 yd) away and the shock from the detonation knocked out her turbines.

[11] On the night of 12/13 April, Commander (Fregattenkapitän) Erich Bey, the senior surviving German officer, received word to expect an attack the following day by British capital ships escorted by a large number of destroyers and supported by carrier aircraft.

The other operable destroyers joined Z19 Hermann Künne as she fell back and engaged the British ships at long range from behind a smoke screen.

By the early afternoon, the Germans had exhausted most of their ammunition and Bey ordered his ships to retreat to the Rombaksfjorden (the easternmost branch of the Ofotfjord), east of Narvik, where they might attempt to ambush any pursuing British destroyers.

She had fired off all of her ammunition, including practice and star shells; her depth charges were rigged for demolition and they were set off once the crew had abandoned ship.