Sirius was assigned to the Naval Transportation Service carrying cargo and passengers in support of fleet units and bases.

Sirius continued her resupply operations to various United States naval bases and fleets until 1937 when she began making runs to Midway Island.

In early 1942, Sirius was attached to the United States Pacific Fleet and left San Pedro, California, on 1 March, with a convoy for Pearl Harbor.

The most noteworthy event of this period was when she transported 35 Imperial Japanese Navy prisoners (recovered from the sunken aircraft carrier Hiryü) from Midway to Pearl Harbor in June 1942.

Sirius decommissioned on 26 April 1946; was struck from the Navy List on 5 June; transferred to the Maritime Commission on 1 July 1946; and sold to the Kaiser Co., on 29 September 1947, for scrap.