Amador was laid down under a Maritime Commission contract, MC hull 2103, on 27 December 1943, at Richmond, California, by Kaiser Cargo Inc.; launched on 15 June 1944; sponsored by Mrs. S. J. Davis; acquired by the Navy on 10 August 1944; commissioned on 9 October 1944, decommissioned at Portland, Oregon, on 23 October 1944 to undergo conversion to an ammunition tender by the Commercial Iron Works, and recommissioned on 25 November 1944. Amador got underway early in December for shakedown training off San Pedro, California. She loaded cargo and ammunition at the Mare Island Navy Yard, Vallejo, California, then sailed for Eniwetok on 11 January 1945. The ship reached Eniwetok on the 29th and was routed on to Ulithi. Upon her arrival there on 18 February, Amador was assigned to Service Squadron 10.
Amador remained at Ulithi through 15 March for ammunition handling operations. She next set sail on the 16th for Leyte, Philippines, via Kossol Roads. The ship anchored in Leyte-Samar Naval Base's San Pedro Bay on 22 March and began issuing ammunition to ships of the fleet, as well as reworking defective projectiles and fuses. On 23 October, she moved to Guinan Roadstead, Samar, and began receiving ammunition from ammunition lighters for transportation back to the United States. On 12 November, Amador got underway for Seattle, Washington. She arrived in Puget Sound on 8 December and remained in that area until 29 March 1946, when she began preparations for deactivation. She was decommissioned on 20 June 1946, and her name was struck from the Navy list on 19 July 1946. The ship was transferred to the Maritime Commission on 23 July 1946. She was subsequently sold and fitted out for service as a merchant ship.