[4] After commissioning, Itsukushima was assigned to the Yokosuka Naval District as a reserve and training vessel, making occasional cruises to the South Seas Mandate and Bonin Islands.

At the time of the attack on Pearl Harbor in December 1941, Itsukushima was assigned to the Southern Philippines Striking Force of the IJN 3rd Fleet under the overall command of Admiral Ibō Takahashi, and tasked with mining the San Bernardino Strait.

[4] In January 1942, Itsukushima was assigned to the Netherlands East Indies theatre of operations, supporting the Japanese invasions of Tarakan and Balikpapan in Borneo as flagship of the Second Base Unit under Admiral Sueto Hirose.

On 31 May, Itsukushima was assigned to "Operation KON" (the Relief of Biak), transporting reinforcements from Zamboanga on Mindanao in an effort to counter the American landings.

On 24 August, Itsukushima was attacked by USAAF B-25 Mitchell bombers from the 345th Bomb Group while escorting a convoy near Lahbeh Strait near the Celebes.

However, on 17 October, while transiting the Java Sea under tow, Itsukushima was torpedoed by the Royal Dutch Navy submarine HNLMS Zwaardvisch, and sank at position 5°23′S 113°48′E / 5.383°S 113.800°E / -5.383; 113.800.

[4] On 15 December 2002 a group of divers operating off the dive vessel MV Empress located the wreck of Itsukushima northeast of Bawean Island in the Java Sea.

The much larger forward section rests 350 to 400 m (1,150 to 1,310 ft) from the severed stern and is completely upside down from the bow stem to the break where the three propeller shafts begin to exit the hull.