In May and June, she prepared in the Solomons and the Marshall Islands for the invasion of the Marianas. She sortied from Eniwetok on 17 July with Task Group 53.18 (TG 53.18). Scheduled fire commenced on the 21st in Agana Bay, Guam, as 3rd Marine Division went ashore. Lying close enough offshore to see pillboxes and trenches, "McKee" delivered close support fire through 4 August, when she retired with a group of carriers to New Hebrides.