In November 1944, "Mellette" followed a San Pedro shakedown cruise with a voyage to the Hawaiian Islands for training operations. She conducted amphibious troop, gunnery, and tactical exercises off Maui into January 1945. On 27 January she joined TG 51.1 and got underway for Iwo Jima. With units of the 4th Marine Division embarked, she steamed west, via Eniwetok and Saipan, arriving off the Volcano Islands to participate in the initial assault 19 February. She remained off the eastern beaches of Iwo Jima for the next 6 days, unloading supplies and taking on casualties. On the 25th she sailed for Saipan where she disembarked her wounded passengers and began preparations for the upcoming Okinawa campaign.