The Eldorado was launched on October 26, 1943 as Monsoon by the North Carolina Shipbuilding Company in Wilmington, North Carolina, under a Maritime Commission contract, sponsored by Mrs. P. A. Peeples; transferred to the US Navy on February 1, 1944; converted by Bethlehem Steel Corporation in Brooklyn, New York; and commissioned on August 25, 1944, with Captain Jesse Wallace in command.
In 1945, at the end of the war, the Eldorado was at Manila preparing for the proposed invasion of the Japanese home islands. It returned to Pearl Harbor in October where Admiral Turner and his staff debarked. Alternately at Pearl Harbor and at west coast ports, the Eldorado continued to serve as the flagship for succeeding amphibious commanders in the Pacific. There were two exceptions: From April to September 1947 and again from January to July 1949, it flew the flag of Commander, Naval Forces, Western Pacific, and cruised to Chinese waters. During the second tour, the Eldorado departed Shanghai only a short time before that city fell to the Communists.
With the outbreak of the Korean War in June 1950, the Eldorado was ordered to the Far East. The Eldorado was the flagship for Rear Admiral Lyman A. Thackrey, Commander, Amphibious Group 3, and it acted as standby for the during the invasion of Inchon, South Korea, and coordinated and controlled the logistics operations. In October 1950, it sailed to Riwon to support the continued northwest advance of United Nations troops. Returning to Japan in November, the Eldorado was ordered again to Inchon to direct the evacuation. It was at Inchon again in the spring and summer of 1951, and in June hoisted the flag of Vice Admiral Ingolf N. Kiland, Commander, Amphibious Forces, Pacific Fleet. The Eldorado was visited by Generals Matthew B. Ridgway and Van Fleet, and the commanding generals of the British troops and Turkish Brigades during its stay at Inchon, and sent the first pictures of the Korean Armistice Agreement talks to the outside world. The Eldorado returned to the States and became the flagship for Rear Admiral W. E. Moore, Commander, Amphibious Group 1, in October 1952. It sailed for the Far East where Admiral Moore assumed command of TF 90's amphibious forces. During this tour, the Eldorado assisted the Japanese Government during the floods at Fukuoka, and directed Operation Big Switch, the transportation of Chinese and Korean prisoners of war from the camps at Cheju Do and Koje-do to the port of Inchon for repatriation.
The Eldorado returned to the west coast in the fall of 1953, and continued to serve as the flagship for Amphibious Group 1, now commanded by Rear Admiral Lorenzo Sabin, Jr., until June 1954. It embarked Vice Admiral Thomas G. W. Settle, Commander, Amphibious Forces, Pacific, until August. On February 15, 1955, the Eldorado sailed for Keeling, Formosa, where it operated as the flagship for Vice Admiral Alfred M. Pride, Commander, 7th Fleet, until August 17. The Eldorado returned to San Diego for amphibious exercises, and on December 13, Rear Admiral George C. Towner broke his flag on board as Commander, Amphibious Group 3 and Eastern Pacific. In the summer of 1956, the Eldorado sailed to arctic waters with Army officers embarked, to resupply bases at Wainwright, Alaska, and Point Barrow, Alaska. From December 1956 to January 1957, it was the flagship for Vice Admiral Carl F. Espe, Commander, Amphibious Forces, Pacific, and during the next month, for Vice Admiral Robert L. Dennison, Commander, United States First Fleet. From June 1957 through 1960, the Eldorado served as the flagship for four successive commanders of Amphibious Group 1, Rear Admirals Frederick C. Stelter, Jr., Charles K. Duncan, Charles O. Triebel, and Charles C. Kirkpatrick. The only interruption to this service was in October and November 1958, when it served Vice Admiral John Sylvester, Commander, Amphibious Forces, Pacific, as flagship. In addition to operations along the west coast from her home port at San Diego, the Eldorado took part in Arctic supply operations once more in the summer of 1957, and cruised to the Far East from January to May 1958, and again from December 1959 into 1960. During the second of these, as the flagship, the Eldorado participated in exercise "Blue Star," a joint Navy-Marine and Nationalist Chinese Navy-Marine amphibious operation off southern Taiwan. In April and May, the Eldorado visited ports in Indonesia and Australia, participating in Australia's 18th annual celebration of the Battle of the Coral Sea before returning to San Diego on May 31 where it remained. The Eldorado was the flagship for the eight-week expedition for the 5th MEB during the Cuban Missile Crisis and then participating in local operations through 1962.
The Eldorado served as the flagship for the Commander Amphibious Forces Pacific Fleet in rotation with and Mount McKinley during the Vietnam War. In 1967, the ship received the Navy Meritorious Unit Commendation for its role in twelve amphibious assaults in Vietnam, in conjunction with the Amphibious Ready Group and the Marine Special Landing Force.
In January 1969, Eldorados designation was changed to LCC-11. Also, in 1969, USS Eldorado LCC11 was awarded the Navy Unit Commendation for her actions concerning command and control during Operation Bold Mariner, the largest amphibious landing since WWII. The operation occurred in the Batangan Peninsula area of South Vietnam.
During the Eldorado's decommissioning in November 1972, it was berthed adjacent to the at the 32nd Street Naval Station in San Diego, and transferred much of her equipment to its successor prior to scrapping. The Eldorado received two battle stars for its World War II service and eight battle stars for its Korean War service.