In May, "John Rodgers" operated out of Guadalcanal screening convoys and bombarding enemy positions. Early in June she sailed to the Marshall Islands to prepare for the Marianas Campaign and departed Eniwetok on 17 July with the Guam invasion force. Beginning on 21 July, "John Rodgers" fired more than 3,600 rounds at targets on Guam helping to knock out enemy troop concentrations and defensive works. The destroyer remained in the Mariana Islands until 4 August and provided antisubmarine screen for transports bringing reinforcements.