Okanogan was laid down 10 August 1944, under Maritime Commission (MARCOM) contract, MCV hull 568, by Permanente Metals Corporation, Yard No.

[3] Okanogan's first mission began 16 February 1945, when she sailed from San Francisco bound for Hawaii with the staff of Transport Division 57, along with a number of Navy, Marine, and civilian passengers.

[3] Only brief periods in West Coast ports broke her heavy schedule, brought on by the urgent need to redeploy troops for occupation duties and to return combat veterans to the United States.

She completed a voyage at San Francisco 9 January 1946, and a month later sailed for Norfolk, Virginia, her home port for operations with the Atlantic Fleetfor the next four years.

[3] As the Navy and Marines sharpened the techniques of warfare born in wartime, Okanogan made reserve training cruises and took part in maneuvers and exercises along the eastern seaboard, in the Caribbean, and, in the fall of 1949, in the Hawaiian Islands.

[3] Okanogan rejoined the US Pacific Fleet upon the outbreak of the Korean War, and in August 1950, loaded part of the 1st Marine Division at San Diego for Japan.

The skill with which the operation was executed won acclaim from General MacArthur, who exclaimed "...the Navy and Marine Corps have never shone brighter …".

[3] Okanogan evacuated three thousand refugees from Chinampo in December; one more was born at sea and later named for the ship by its grateful parents.

She transported the staff of Landing Ship Flotilla One to Kojedo, Korea, and carried out amphibious exercises off Japan, before returning to Long Beach in December.

Her first mission, in preparing to return to Long Beach, was the delivery of ten landing craft to the Laotian government; her second, the loading of Thai and Vietnamese art treasures for a planned tour of the United States.

Okanogan was in Portland Oregon for overhaul, San Diego for refresher training and amphibious exercises off the coast of California.

Her boats operated 18 to 20 hours a day in this essential support for build-up of one of the major bases for the Allied effort to repel Communist aggression.

[3] Okanogan returned to Long Beach 17 December, and in June and July 1966, again voyaged to South Vietnam, carrying Marine communications technicians.