Following trial runs in Long Island Sound, "Blue Ridge" departed New York on 8 October 1943, to train in the Chesapeake Bay Area out of Norfolk, Virginia. On 1 November, the ship put to sea with two destroyers, bound for the South Pacific. After transit of the Panama Canal, "Blue Ridge" called at the Society, New Caledonia and Fiji Islands, en route to Brisbane, Australia, arriving on 16 December 1943. She pulled out of Brisbane three days later for Milne Bay, New Guinea where 24 December 1943, she became the flagship of Rear Admiral Daniel E. Barbey, USN, Commander Seventh Amphibious Force. She served as the command ship for amphibious operations westward along the New Guinea Coast until 13 October 1944. On that day, "Blue Ridge" left Hollandia (currently known as Jayapura) as the flagship of Rear Admiral Barbey's Northern Attack Force bound for the liberation of the Philippine Islands.