Assigned to Task Group 79.3 for the impending amphibious assault on Leyte, she departed Seeadler Harbor on 14 October in company with Transport Division 7 and rendezvoused with Attack Group Able. In the early hours of "A-day," 20 October, the formation fought the strong currents of the Surigao Strait and drove off a Japanese dive bomber before arriving in the outer transport area. While the battleships delivered a pre-assault bombardment, "Thuban" began lowering her boats. Throughout the morning, she unloaded cargo; and her landing craft joined the assault waves which raced to the beach. Although interrupted by calls to general quarters and the necessity to make smoke when an air attack was imminent, for three days she discharged a steady stream of vital ammunition, engineering equipment, trucks, trailers, and rations for the troops on shore. On the morning of the 21st, two enemy planes came in low, evading detection, and dropped bombs near the attack transport , astern of "Thuban". On the 23rd, she unloaded the last of her cargo; departed the Philippines; and steamed via Manus to arrive at Oro Bay, New Guinea, on 4 November.