The attack transport spent the rest of the month getting ready for her shakedown by holding drills and taking on supplies.

She first stopped in the Marshall Islands then moved on to Guam to unload part of her cargo and to disembark some of her passengers, before delivering the remainder of both to Saipan.

After stopping at Tacloban on Leyte, Barnwell transferred 23 landing craft to the boat pool at Samar and then headed back to the United States, carrying sailors and marines.

Following a stop at Pearl Harbor en route, she disembarked her passengers and unloaded her cargo at San Francisco before starting voyage repairs.

After delivering passengers and mail to both Guinan Harbor on Samar and Tacloban on Leyte, the attack transport sailed for the Admiralty Islands on 10 August.

Bound for San Francisco at first, she received orders diverting her to Seattle while en route, and Barnwell made that port on 12 November.

Released from such tasks on 15 January 1946 by the arrival of USS American Legion (APA-17), Barnwell left California soon thereafter on her way to the east coast to be deactivated.