Yamashiro was modernized between 1930 and 1935, with improvements to her armor and machinery and a rebuilt superstructure in the pagoda mast style. Nevertheless, with only 14-inch guns, she was outclassed by other Japanese battleships at the beginning of World War II, and played auxiliary roles for most of the war.

By 1944, though, she was forced into front-line duty, serving as the flagship of Vice-Admiral Shōji Nishimura's Southern Force at the Battle of Surigao Strait, the southernmost action of the Battle of Leyte Gulf. During fierce night fighting in the early hours of 25 October against a superior American and Australian force, Yamashiro was sunk by torpedoes and naval gunfire. Nishimura went down with his ship, and only 10 crewmembers survived.