"Pillau" spent the majority of her career in II Scouting Group, and saw service in both the Baltic and North Seas. In August 1915, she participated in the Battle of the Gulf of Riga against the Russian Navy, and on 31 May – 1 June 1916, she saw significant action at the Battle of Jutland. She was hit by a large-caliber shell once in the engagement, but suffered only moderate damage. She assisted the badly damaged battlecruiser reach port on 2 June after the conclusion of the battle. She also took part in the Second Battle of Heligoland Bight, though was not damaged in the engagement. "Pillau" was assigned to the planned, final operation of the High Seas Fleet in the closing weeks of the war, but a large scale mutiny forced it to be canceled.