During the early stages of World War I, from 1913–1916, Porębski was captain of the battleship with the Russian Black Sea Fleet and active in combat operations off of Bulgaria. Porębski was promoted to rear admiral on April 19, 1916 and reassigned to command the cruiser squadron of the Black Sea Fleet. He went into the reserves from November 1916, but was recalled in early 1917, and was placed in command of the fortifications guarding the Gulf of Finland. He then served as head of the Maritime Department for the Northwestern Front.