Following shakedown off southern California, Orion got underway for Pearl Harbor 23 November 1943. Arriving there on the 28th, she received her first submarine, USS Gar (SS-206) alongside for repairs two days later. On 10 December she steamed for Australia, arriving at Fremantle 5 January 1944 to begin her mission of maintaining the material readiness of, and an adequate stock of supplies for, submarines operating in the southwest Pacific. She remained in Western Australia until 6 August 1944 when she proceeded to Mios Woendi, Indonesia to establish Advanced Submarine Base Able. Arriving 26 August 1944, she serviced 24 submarines, and 466 surface vessels, before being relieved, 9 December 1944, by USS Griffin (AS-13).