"McNair" departed New York on 5 March 1944 for the Pacific. By 14 June, as a unit of Destroyer Squadron 54 (DesRon 54), she was in the screen for the battleships that opened their guns against Japanese shore installations on Saipan. For the next 19 days, she provided fire support and carried out antisubmarine patrols. On 3 July, she was detached from TF 52 to escort ships between Eniwetok and Saipan. Rejoining that force on the 25th, she provided fire and screening support for the invasion of Tinian. Detached again 2 August, "McNair" steamed to Guadalcanal to prepare for the next offensive operation, the Palaus. From 6–21 September, she supported the land forces effecting the capture and occupation of the southern Palaus with counterbattery and harassing fire. After the battle of Angaur, she sailed south to Manus Island, the staging area for the Leyte invasion.