With the Aleutians recaptured, Mississippi returned to the west coast for an overhaul at San Francisco. On 19 October she departed to participate in the invasion of the Gilbert Islands in November. As a part of the Northern Attack Force (Task Group 52.2) they began bombarding Makin Island on 20 November. While bombarding the island a turret explosion killed 43 men (a similiar incident occurred earlier in her career on June 1924 which killed 48 men.)

The task group then sailed to the Marshall Islands in January 1944 and Mississippi began bombarding Kwajalein on 31 January. She continued her shelling for about the next month - on 20 February she shelled Taroa and the next day Wotje. On 20 March 1944 four battleships, including Mississippi, shelled Kavieng, New Ireland, as a diversion from the Army invasion of Emirau Island. With the Marshall Island operation over she departed again for an overhaul at Puget Sound Navy Yard where she remained for about the next six months.

Mississippi returned to the Pacific to support the landings in the Palau Islands as part of Task Force 3 on 12 September. Pre-invasion bombardment against Peleliu and Anguar islands commenced the next day and continued for the following days. For her next operation for the reconquest of the Philippines she was a member of the Northern Attack Force of Task Force 79. She commenced shelling the east coast of Leyte on 19 October and became a part of the battleship lineup at Surigao Strait. The resulting historic battle on 24/25 October would cost the Japanese two battleships and three destroyers but Mississippi fired only one salvo. She remained in the area until 16 November before sailing to Admiralty Islands.

In the first week of January 1945, she sailed from San Pedro Bay to Lingayen Gulf for more bombarding which began on 6 January. Throughout the next several days she continued shelling and provided fire support for the landings until 10 February. During the initial days she was hit by a kamikaze around one of her 5in gun mounts damaging her hull near the waterline. She returned to Pearl Harbor for repairs and modifications. She landed several more anti-aircraft guns at the insistance of her captain and her 5in/51cal casemate guns were removed and plated over. Eight additional 5in/25cal dual purpose guns were added which doubled the quantity of that type of gun.

With repairs and refit complete she departed to prepare for the invasion of Okinawa. As a part of Unit 5 in Task Force 54, she joined in the shelling of Okinawa on 6 May 1945. On 5 June another kamikaze smashed into her starboard side near her bridge but she continued supporting the Okinawa invasion until 16 June. When the war ended on 15 August she sailed into Toyko Bay as a member of Halsey's Task Force 38 to witness the surrender on 2 September.

After the war Mississippi was converted to AG 128 (later EAG 128) as a gunnery trainer and experimental ship testing new weapons into the 1950's. She was finally decommissioned as EAG 128 on 17 September 1956 and sold for scrap to Bethlehem Steel Company on 28 November. She was awarded eight battle stars for her service in World War II.