"Admiral Spaun" served as the flotilla leader of the Second Torpedo Flotilla at the outbreak of World War I and was stationed out of the naval base at Cattaro. She saw limited action during the first year of the war, and following Italy's declaration of war on Austria-Hungary in May 1915, the cruiser participated in a bombardment of the Italian coastline. Throughout the rest of 1915, "Admiral Spaun" engaged in various operations across the Adriatic Sea. While she was involved in missions centred mostly around Trieste in the northern Adriatic for the rest of the war, "Admiral Spaun" also participated in many of Austria-Hungary's naval operations as far south as the Otranto Barrage and the Strait of Otranto, alongside the "Novara"-class cruisers.