She was laid down under a United States Maritime Commission contract (MCV hull 44) on 9 July 1944 at Wilmington, Los Angeles, by the California Shipbuilding Corporation; launched on 14 September 1944; sponsored by Mrs. L.D.

Worsham; delivered to the Moore Dry Dock Company, Oakland, California, on 24 September 1944 for completion; acquired by the U.S. Navy and placed in commission, 8 January 1945.

After shakedown and amphibious training exercises off San Diego, California, Arenac took on a load of cargo and departed for Hawaii.

On 3 February 1945, Arenac was designated the flagship for Combat Transport Division (COMTRANSDIV) 68, under the command of Commodore Chauncey Crutcher.

While awaiting clearance to proceed to the beaches to unload her cargo Arenac underwent frequent alerts for enemy air attack.

She moored off Hagushi Beach on 3 June, finished unloading her cargo and passengers by the 5th, and then began taking on personnel for evacuation from Okinawa.

"High-point" Navy and Army personnel were loaded for transport to San Francisco for discharge, but while en route, Arenac was diverted to Seattle, Washington instead, and arrived there on 25 November 1945.

The ship debarked the Navy replacement passengers, then four days later departed for Nagoya, arriving on 6 January 1946, embarking veterans for return to stateside and discharge.

The Operation Magic Carpet assignment was completed in March 1946, and the ship was ordered to the East Coast of the United States for deactivation.