Porębski attended mine warfare school on commissioning into the Imperial Russian Navy, and from 1895 to 1899 served aboard the on which he voyaged to the Mediterranean and then to the Far East with a visit to Nagasaki, Japan in 1896. He was promoted to lieutenant on April 13, 1897, after his return to Russia, and continued his studies in mine warfare. He was then assigned to the from 1899-1901. On December 1, 1901, he became the executive officer on the cruiser , whose construction he had been sent to oversee at the Schichau-Werke shipyards in Danzig, Germany. Assigned with "Novik" to the Russian Pacific Fleet, he was promoted to Captain Lieutenant on April 17, 1905. Novik played an active role in the Russo-Japanese War, especially at the Battle of the Yellow Sea and the Battle of Korsakov.