At the start of the Pacific War, on 15 October 1941, Miyazaki was promoted to captain and served on the staff of the IJN 5th Fleet. He subsequently was promoted to captain and served as commander of Destroyer Division 17 in the Southwest Pacific from 17 June to 18 December 1943, followed by a posting as senior instructor at the Torpedo School in Oppama.
At the start of the Pacific War, on October 15, 1941, Miyazaki was promoted to captain and served in the staff of the IJN 5th Fleet. He later became captain and commanded Destroyer Division 17 in the Southwest Pacific from June 17 to December 18, 1943, before being assigned as a senior instructor at the Torpedo School in Oppama.