Karlsruhe was laid down in July 1926 at the Deutsche Werke shipyard in Kiel, launched in August 1927, and commissioned into the Reichsmarine in November 1929.

She landed troops at Kristiansand, but while returning to Germany on 9 April, she was struck by a torpedo from the Royal Navy submarine HMS Truant and severely damaged.

In 1935, she had more modifications made, including the installation of a pole mast aft of the funnels, along with an aircraft catapult amidships with a crane to handle floatplanes.

[5] Structural weaknesses in her mostly-welded hull plating caused significant damage, and the cruiser was forced to put into San Diego in April for repairs.

After emerging from this refit, she conducted sea trials and then joined the non-intervention patrols during the Spanish Civil War, though she only remained off Spain for a few months.

[5] On 4 January, Karlsruhe and the minelayer Schiff 23 were sent to intercept the Swedish steamer Konung Oscar, which was transporting Polish refugees from Riga to Sweden.

[4] The invasion force departed Bremerhaven early on 8 April 1940 with Kapitän zur See Friedrich Rieve aboard Karlsruhe commanding.

The cruiser turned in the fjord to bring her full broadside into action; the artillery duel lasted for about two hours before heavy fog again covered the port, forcing both sides to cease fire.

The British submarine HMS Truant was positioned outside the fjord, and when her crew spotted the German ships, she fired a spread of torpedoes.

[7] Karlsruhe took evasive action, but one torpedo struck her on the starboard side amidships, blasting a large hole in the hull and allowing thousands of tons of water to flood in.

With those pumps inoperable, Rieve decided there was no hope of saving Karlsruhe and issued the order to abandon ship two hours after the attack.

The report concluded that since the ship was still afloat after two hours, and two additional torpedoes were required to sink her, it might have been possible to take her under tow back to Kristiansand or another port.

The Norwegian power grid operator Statnett conducted a sonar survey in April 2017 that located the wreck but did not identify it at the time.

The vessel lies upright on the sea floor, 15 m (49 ft) from the submerged power line between Denmark and Norway, operated by Statnett.

[9] Stattnet sent another expedition on 30 June 2020 with the survey vessel Olympic Taurus to conduct an investigation of the wreck using remotely operated underwater vehicles after a severe storm, to confirm that the cable had not been damaged.