After the outbreak of World War I in July 1914, she was assigned to the reconnaissance forces in the Baltic and was tasked with protecting the German coast from Russian attacks.

Both were ordered under the Second Naval Law of 1900, which called for a force of fourteen armored cruisers that would be able to serve in Germany's colonial empire and scout for the main German fleet in home waters.

Prinz Adalbert and the light cruiser Berlin escorted the Kaiser's yacht Hohenzollern to Sweden for a visit to King Oscar II in July 1905.

The following month, she joined the light cruisers Undine and Nymphe for training maneuvers off Swinemünde; the exercises were to test the ships against a simulated night attack by torpedo boats.

[10] The ship served as the flagship of the III Scouting Group, under Konteradmiral Johannes Merten, who would go on to command the Ottoman fortifications at the Dardanelles during World War I.

Prinz Adalbert was then decommissioned in Kiel on the 29th, with the armored cruiser Blücher taking her place as the fleet's gunnery training ship.

[11] At the outbreak of World War I in July 1914, Prinz Adalbert was brought into front-line service with the fleet, and Kapitän zur See Andreas Michelsen took command of the ship.

The ship was briefly detached to guard the Great Belt after the Germans received false intelligence suggesting that British warships would try to penetrate the Baltic.

On the 15th, she sortied with the light cruisers Augsburg, Lübeck, Amazone, and Thetis and several torpedo boats for a reconnaissance sweep toward Åland; the ships returned to port on 18 December without having engaged Russian forces.

Another sweep followed on 27–29 December, this time to cover a sortie by the five Kaiser Friedrich III-class battleships of V Battle Squadron toward Gotland.

[13] On 6 January 1915, Prinz Adalbert, Thetis, Augsburg, Lübeck, and several torpedo boats and U-boats went on a patrol toward Utö, where they discovered a Russian submarine base.

[16] Behring conducted one last operation from 13 to 17 April, with Prinz Adalbert, Thetis, and Lübeck, to support the minelayer Deutschland, which laid a minefield off Dagö.

At the same time, Michelsen was promoted to Hopman's chief of staff, with his place as Prinz Adalbert's commanding officer being taken by Kapitän zur See Wilhelm Bunnemann.

At this time, Generalfeldmarschall ('General Field Marshal') Paul von Hindenburg, the commander-in-chief of German forces on the Eastern Front, ordered a major assault on Libau.

[20] On 1 July, the minelayer SMS Albatross, escorted by the cruisers Roon, Augsburg, and Lübeck and seven destroyers, laid a minefield north of Bogskär.

While returning to port, the flotilla separated into two sections; Augsburg, Albatross, and three destroyers made for Rixhöft while the remainder of the unit went to Libau.

Augsburg and Albatross were intercepted by a powerful Russian squadron commanded by Rear Admiral Bakhirev, consisting of three armored and two light cruisers.

[21] Commodore Johannes von Karpf, the flotilla commander, ordered the slower Albatross to steam for neutral Swedish waters and recalled Roon and Lübeck.

Albatross was grounded off Gotland and Augsburg escaped, and the Russian squadron briefly engaged Roon before both sides broke contact.

On 21 September, Prinz Adalbert joined a sortie to the Gulf of Finland with the battleships Braunschweig, Elsass, Mecklenburg, Schwaben, and Zähringen and the light cruiser Bremen.

Another operation followed on 5 October; this was in company with Prinz Heinrich and Bremen, and was to cover a minelayer as it laid a field to the northwest of Östergarn.

The ship was steaming some 20 nmi (37 km; 23 mi) west of Libau, en route to her patrol area, in company with a pair of destroyers on 23 October when she was intercepted by the British submarine HMS E8.