She moved into Leyte Gulf on 18 October, two days before the actual landings, to cover preinvasion minesweeping and underwater demolition team operations. Her  shells also contributed to the preinvasion bombardment of the objective. After the 20 October landings, the warship delivered call fire in support of the troops advancing ashore and defended the invasion fleet against the heavy enemy air attacks launched against it. In the latter role, she claimed one unassisted kill. When the Japanese launched their three-pronged surface attack to break up the Leyte assault, "Welles" joined the screen of Vice Admiral Jesse B. Oldendorf's line of old battleships which virtually annihilated the enemy force which attempted to push through the Surigao Strait south of Leyte on the night of 24/25 October. Soon thereafter, she concluded her part in the Philippine operation and retired to Ulithi Atoll where she joined the screen of the Fast Carrier Task Force.