The Fast Carrier Task Force, with "Stanly" in its screen, opened the air assault on the Marianas on 11 June, sending sorties to bomb and strafe Guam, Rota, Tinian, and Saipan. The pilots of TF 58 added Pagan Island to their itinerary on the 12th and again on the 13th. On 15 and 16 June, "Stanly" escorted Task Group 58.4 while its planes attacked Iwo Jima and Chi Chi Jima in the Bonins. On the 18th, the task group rejoined TF 58 just in time to witness the Battle of the Philippine Sea, in which the United States Navy broke Japanese naval airpower. On 20 June, "Stanly" participated in the bombardment of Guam and Rota and, two days later, moved off to defend and support the American forces on Saipan. She continued patrols and periodic bombardments around Saipan until 3 July, when she retired with TG 58.4 to Eniwetok. The destroyer returned to the Marianas on 18 July and screened the carriers until the 31st, when she was ordered back to the United States.