The ship was part of the Second Pacific Squadron sent to the Far East during the Russo-Japanese War of 1904–05, and served as the flagship of Rear Admiral Baron Dmitry von Fölkersam.

She carried a maximum of 2,060 long tons (2,090 t) of coal which allowed her to steam for 6,200 nautical miles (11,500 km; 7,100 mi) at a speed of 10 knots (19 km/h; 12 mph).

The secondary armament consisted of eleven Canet 6-inch (152 mm) quick-firing (QF) guns, mounted in casemates on the sides of the hull and in the bow, underneath the forecastle.

After repairs, the ship resumed her voyage to the Far East, but she was recalled to join the Baltic Fleet on 12 February 1904, following the start of the Russo-Japanese War three days previously.

[6][7] After arrival at St. Petersburg in April, Oslyabya was fitted with 4.5-foot (1.4 m) Barr & Stroud rangefinders, telescopic gun sights, a new ventilation system, and Telefunken radio equipment.

[11] When his ships reached the port of Tangier, Morocco, on 28 October, Rozhestvensky ordered his older battleships, under the command of von Fölkersam, to go through the Mediterranean and Red Sea to rendezvous with his main force in Madagascar.

Oslyabya's Captain 1st Rank Vladimir Ber became the commander of the Second Division, while Nebogatov had no idea that he was now the squadron's de facto second-in-command.

[13] While figures are not available for Oslyabya, one Russian account after the battle said that the Borodinos were approximately 1,700 long tons (1,700 t) overweight as they were overloaded with coal and other supplies that were stored high in the ships, reducing their stability.

During the subsequent battle Oslyabya led the Second Division of the squadron and was initially the target of at least two battleships and a pair of armored cruisers when the Japanese opened fire at 14:10.

Almost immediately, the shells began inflicting damage, knocking out the rangefinder, wounding the gunnery officer and severing the cables connecting the guns to the Geisler fire-control system.

[7][16][17] The ship sank a few minutes later with her starboard propeller still turning, first all-steel battleship to be sunk by naval gunfire alone,[18] taking Ber and 470 of her crew with her.