After a tour at Naval Torpedo Station Newport, Commander Healy reported on 13 March 1941 as Damage Control Officer on board the aircraft carrier USS Lexington.

From there she proceeded to Pearl Harbor, and after arrival on 11 December spent several weeks training in Hawaiian waters with Yorktown and other ships which would become the famous Task Force 58 (TF 58) under Vice Admiral Marc Mitscher.

After the raid Healy and the carriers steamed to the Marianas, fought off several air attacks 22 February, and delivered important strikes against Saipan, Tinian, and Guam, America's next objectives in the Pacific.

After a stop at Espiritu Santo the ships struck the Palau Islands 30 March, and after beating off Japanese air raids launched an attack on Yap and Ulithi the next day.

After a period of intensive training and preparation, she departed Majuro on 6 June for the invasion of the Marianas, a spectacular amphibious operation to be carried out nearly 1,000 miles (1,800 km) from the nearest advance base, Eniwetok.

Two days later, Healy and the other ships steamed out to join Admiral Mitscher's carrier task force as the Japanese made preparations to close the Marianas for a decisive naval battle.

With able assistance from American submarines, Mitscher succeeded in sinking two Japanese carriers in addition to inflicting fatal losses on the enemy naval air arm during "The Great Marianas Turkey Shoot" on 19 June.

Healy was detached that date and joined a carrier task group for direct support of the Peleliu invasion, the next step on the island road to Japan.

As troops stormed ashore at Leyte for the historic return to the Philippines, Healy and her carrier group began direct support of the operation, blasting airfields on southern Luzon.

Healy joined Rear Admiral Frederick C. Sherman's Task Group 38.3 (TG 38.3), near Luzon 24 October which was attacked early in the day by land-based aircraft.

Planes of the task group struck out at the ships of Vice Admiral Takeo Kurita in the Sibuyan Sea, sinking Musashi and damaging other heavy units of the Japanese forces.

Strikes on 5 November crippled airfields on Luzon, hit shipping in Manila Bay, and fought off air attacks by Japanese planes against the fleet.

After riding out the terrible typhoon which sank Hull, Monaghan, and Spence, Healy searched for survivors from the lost ships before returning to Ulithi with her carrier group 24 December.

With Healy and other destroyers in the protective screen, carrier planes supplied close support for the invasion of the island on 19 February, and continued for 3 days before departing for strikes against Japanese home air bases.

Leaving the carrier group, Healy next was assigned to the battleships designated to bombard Iwo Jima, and remained off the island patrolling and screening from 4–27 March.

After repairs and additional training, Healy again got underway for the combat zone 20 June 1945, departing the Hawaiian area on 2 August with New Jersey and other ships for the western Pacific.

Healy then participated in local operations, spent a month as training ship for Naval Mine Warfare School, Yorktown, Va., and arrived Norfolk on 19 March 1957.