The ship was laid down as Ticonderoga on 26 January 1943 by Bethlehem Steel Co., Quincy, Massachusetts It was renamed Hancock 1 May 1943 in response to an offer from the John Hancock life insurance company to conduct a special bond drive to raise money for the ship if that name was used. (The shipyard at Quincy was in the company's home state.) CV-14, laid down as Hancock and under construction at the same time in Newport News, Virginia, took the name Ticonderoga instead.

The company's bond drive raised enough money to both build the ship and operate it for the first year. The ship was launched 24 January 1944 by Mrs. Juanita Gabriel-Ramsey, the wife of Rear Admiral DeWitt Clinton Ramsey, Chief of the Bureau of Aeronautics. Hancock was commissioned 15 April 1944, with Captain Fred C. Dickey in command.

World War II

After fitting out in the Boston Navy Yard and shake-down training off Trinidad and Venezuela, Hancock returned to Boston for alterations on 9 July 1944. She departed Boston on 31 July en route to Pearl Harbor via the Panama Canal and San Diego, and from there sailed on 24 September to join Admiral W. F. Halsey's 3rd Fleet at Ulithi on 5 October. She was assigned to Rear Admiral Gerald F. Bogan's Carrier Task Group 38.2 (TG 38.2).

Hancock got underway the following afternoon for a rendezvous point 375 nmi (690 km) west of the Marianas where units of Vice Admiral Mitscher's Fast Carrier Task Force 38 (TF 38) were assembling in preparation for the daring cruise to raid Japanese air and sea bases in the Ryūkyūs, Formosa, and the Philippines. Thus enemy air power was paralyzed during General MacArthur's invasion of Leyte. When the armada arrived off the Ryukyu Islands on 10 October 1944, Hancock's planes rose off her deck to wreak destruction upon Okinawan airfields and shipping. Her planes destroyed seven enemy aircraft on the ground and assisted in the destruction of a submarine tender, 12 torpedo boats, 2 midget submarines, four cargo ships, and a number of sampans. Next on the agenda were Formosan air bases where on 12 October Hancock's pilots downed six enemy planes and destroyed nine more on the ground. She also reported one cargo ship definitely sunk, three probably destroyed, and several others damaged.

As they repelled an enemy air raid that evening, Hancock's gunners accounted for a Japanese plane and drove off countless others during seven hours of uninterrupted general quarters. The following morning her planes resumed their assault, knocking out ammunition dumps, hangars, barracks, and industrial plants ashore and damaging an enemy transport. As Japanese planes again attacked the Americans during their second night off Formosa, Hancock's antiaircraft fire brought down another raider which crashed about 500 yd (460 m) off her flight deck. On the morning of the third day of operations against this enemy stronghold Hancock lashed out again at airfields and shipping before retiring to the southeast with her task force. As the American ships withdrew a heavy force of Japanese aircraft roared in for a parting crack. One dropped a bomb off Hancock's port bow a few seconds before being hit by the carrier's guns and crashing into the sea. Another bomb penetrated a gun platform but exploded harmlessly in the water. The surviving attackers then turned tail, and the task force was thereafter unmolested as they sailed toward the Philippines to support the landings at Leyte.

On 18 October, she launched planes against airfields and shipping at Laoag, Aparri, and Camiguin Island in Northern Luzon. Her planes struck the islands of Cebu, Panay, Negros, and Masbate, pounding enemy airfields and shipping. The next day, she retired toward Ulithi with Vice Admiral John S. McCain, Sr.'s TG 38.1.

She received orders on 23 October to turn back to the area off Samar to assist in the search for units of the Japanese fleet reportedly closing Leyte to challenge the American fleet, and to destroy amphibious forces which were struggling to take the island from Japan. Hancock did not reach Samar in time to assist the heroic escort carriers and destroyers of "Taffy 3" during the main action of the Battle off Samar, but her planes did manage to lash the fleeing Japanese Center Force as it passed through the San Bernardino Strait. Hancock then rejoined Rear Admiral Bogan's Task Group with which she struck airfields and shipping in the vicinity of Manila on 29 October 1944. During operations through 19 November, her planes gave direct support to advancing Army troops and attacked Japanese shipping over a 350 mi (560 km) area. She became flagship of the Fast Carrier Task Force (TF 38) on 17 November 1944 when Admiral McCain came on board.

Unfavorable weather prevented operations until 25 November, when a kamikaze roared toward Hancock, diving out of the sun. Antiaircraft fire exploded the plane some 300 ft (90 m) above the ship, but a section of its fuselage landed amidships, and a part of the wing hit the flight deck and burst into flames. Prompt and skillful teamwork quickly extinguished the blaze and prevented serious damage.

Hancock returned to Ulithi on 27 November and departed from that island with her task group to maintain air patrol over enemy airfields on Luzon to prevent kamikazes from attacking amphibious vessels of the landing force in Mindoro. The first strikes were launched on 14 December against Clark and Angeles Airfields as well as enemy ground targets on Salvador Island. The next day her planes struck installations at Masinloc, San Fernando, and Cabanatuan, while fighter patrols kept the Japanese airmen down. Her planes also attacked shipping in Manila Bay.

Hancock encountered a severe typhoon (Cobra) on 17 December 1944 and rode out the storm in waves which broke over her flight deck, some 55 ft (20 m) above her waterline. She put into Ulithi 24 December and got underway six days later to attack airfields and shipping around the South China Sea. Her planes struck hard blows at Luzon airfields on 7–8 January 1945 and turned their attention back to Formosa on 9 January, hitting fiercely at airfields and the Toko Seaplane Station. An enemy convoy north of Camranh Bay, Indochina was the next victim, with two ships sunk and 11 damaged. That afternoon Hancock launched strikes against airfields at Saigon and shipping on the northeastern bulge of French Indochina. Strikes by the fast and mobile carrier force continued through 16 January, hitting Hainan Island in the Gulf of Tonkin, the Pescadores Islands, and shipping in the harbor of Hong Kong. Raids against Formosa were resumed on 20 January. The next afternoon one of her planes returning from a sortie made a normal landing, taxied to a point abreast of the island, and disintegrated in a blinding explosion which killed 50 men and injured 75 others. Again outstanding work quickly brought the fires under control in time to land other planes which were still aloft. She returned to formation and launched strikes against Okinawa the next morning.

Hancock reached Ulithi on 25 January where Admiral McCain left the ship and relinquished command of the 5th Fleet. She sortied with the ships of her task group on 10 February and launched strikes against airfields in the vicinity of Tokyo on 16 February. On that day, her air group, Air Group 80, downed 71 enemy planes, and accounted for 12 more the next. Her planes hit the enemy naval bases at Chichi Jima and Haha Jima on 19 February. These raids were conducted to isolate Iwo Jima from air and sea support when Marines hit the beaches of that island to begin one of the most bloody and fierce campaigns of the war. Hancock took station off this island to provide tactical support through 22 February, hitting enemy airfields and strafing Japanese troops ashore.

Returning to waters off the enemy home islands, Hancock launched her planes against targets on northern Honshū, making a diversionary raid on the Nansei-shoto islands on 1 March before returning to Ulithi on 4 March 1945.

Back in Japanese waters Hancock joined other carriers in strikes against Kyūshū airfields, southwestern Honshū and shipping in the Inland Sea of Japan on 18 March. Hancock was refueling the destroyer Halsey Powell on 20 March when kamikazes attacked the task force. One plane dove for the two ships but was disintegrated by gunfire when about 700 ft (210 m) overhead. Fragments of the plane hit Hancock's deck while its engine and bomb crashed the fantail of the destroyer. Hancock's gunners shot down another plane as it neared the release point of its bombing run on the carrier.

Hancock was reassigned to Carrier TG 58.3 with which she struck the Nansei-shoto islands from 23–27 March and Minami Daito Island and Kyūshū at the end of the month.

When the 10th Army landed on the western coast of Okinawa on 1 April, Hancock was on hand to provide close air support. A kamikaze cartwheeled across her flight deck on 7 April and crashed into a group of planes while its bomb hit the port catapult to cause a tremendous explosion. Although 62 men were killed and 71 wounded, heroic efforts doused the fires within half an hour enabling her to be back in action before an hour had passed.

Hancock was detached from her task group on 9 April and steamed to Pearl Harbor for repairs. She sailed back into action 13 June and attacked Wake Island on 20 June en route to the Philippines. Hancock sailed from San Pedro Bay with the other carriers on 1 July and attacked Tokyo airfields on 10 July. She continued to operate in Japanese waters until she received confirmation of Japan's capitulation on 15 August 1945 when she recalled her planes from their deadly missions before they reached their targets. However planes of her photo division were attacked by seven enemy aircraft over Sagami Wan. Three were shot down and a fourth escaped in a trail of smoke. Later that afternoon planes of Hancock's air patrol shot down a Japanese torpedo plane as it dived on a British task force. Her planes flew missions over Japan in search of prison camps, dropping supplies and medicine, on 25 August. Information collected during these flights led to landings under command of Commodore R. W. Simpson which brought doctors and supplies to all Allied prisoner of war encampments.

When the formal surrender of the Japanese government was signed on board battleship Missouri, Hancock's planes flew overhead. The carrier entered Tokyo Bay on 10 September 1945 and sailed on 30 September embarking 1,500 passengers at Okinawa for transportation to San Pedro, California, where she arrived on 21 October. Hancock was fitted out for Operation Magic Carpet duty at San Pedro and sailed for Seeadler Harbor, Manus, Admiralty Islands on 2 November. On her return voyage she carried 4,000 passengers who were debarked at San Diego on 4 December. A week later Hancock departed for her second Magic Carpet voyage, embarking 3,773 passengers at Manila for return to Alameda, California on 20 January 1946. She embarked Air Group 7 at San Diego on 18 February for air operations off the coast of California. She sailed from San Diego on 11 March to embark men of two air groups and aircraft at Pearl Harbor for transportation toSaipan, arriving on 1 April. After receiving two other air groups on board at Saipan, she loaded a cargo of aircraft at Guam and steamed by way of Pearl Harbor to Alameda, arriving on 23 April.