Following training operations and a transit of the Panama Canal, Xanthus arrived at Pearl Harbor on 20 July to serve there as a repair ship.

On 11 August, she sailed for Adak, Alaska, to join forces massing there for the projected assaults on the Kurils and northern Japan.

As part of Task Group (TG) 40.2, Xanthus proceeded to Japan and arrived at Ominato on 9 September 1945—the same date that Japanese forces there surrendered to Vice Admiral Frank Jack Fletcher.

On 10 February 1946, Xanthus sailed for Qingdao, China, and helped to stabilize troubled conditions there in the wake of the Japanese withdrawal.

As Communist and Nationalist Chinese jockeyed for position in the volatile situation in their country, Xanthus supported American naval activities in that port until sailing for home on 8 April 1946.