Coghlan sailed from San Francisco 22 September 1942 for Pearl Harbor and Kodiak, Alaska, arriving 13 October for convoy and patrol duty. She supported Army landings on Amchatka 12 January 1943, and participated in the bombardment of Gibson Island at the entrance of Chicago Harbor 18 February. On 20 February, she aided in the sinking of a Japanese merchantman. On 15 March she cleared Dutch Harbor with a force to patrol against Japanese shipping south and west of Kiska to prevent reinforcement of enemy-held Attu. On 26 March her group turned a larger Japanese force back in the Battle of the Komandorski Islands. In this action, Coghlan screened Richmond (CL-9), and laid smoke for the disabled Salt Lake City (CL-25). She bombarded Holtz and Chicago Harbors 26 April, and with the southern support group covered the landings on Attu from 11 May to 2 June. Overhauled at San Francisco in July, Coghlan returned to Adak on 13 August for two final weeks on patrol in the Aleutians.
Coghlan sailed 25 August 1943 for Pearl Harbor arriving 1 September. After taking part in the raids on Baker and Tarawa Islands from 15 to 17 September and the attack on Wake on 5 October, Coghlan replenished at Pearl Harbor and sailed on 31 October for escort and screening duties in the assault on the Gilberts. She returned to Pearl Harbor 11 December.
Coghlan sailed from Pearl Harbor 22 January 1944 to screen carriers giving air coverage to the landings in the Marshalls. She returned, screening transports, to Pearl Harbor 8 March for overhaul. On her next cruise, from 14 to 22 April, she escorted a carrier to sea on its way to Majuro, returning to Pearl Harbor 22 April. On 24 May she sailed for Eniwetok, where she joined the screen of landing ships bound for the invasion of Saipan on 15 June. Coghlan gave fire support and patrolled off the island until 23 June. After replenishing at Eniwetok, the destroyer returned to Saipan 17 July to support the landings at Tinian 24 July. After offering fire support until the island was secured 1 August, Coghlan sailed for a brief overhaul at Pearl Harbor.
Coghlan arrived at Manus 8 October, and sailed for the operations in the Philippines 6 November. She conducted convoy escort duty from Humboldt Bay and Palau to Leyte, and supported the landings at Ormoc Bay on 7 and 8 December, firing in the heavy kamikaze attack on the first day. On 9 January 1945 she entered Lingayen Gulf for patrol and screening operations in support of the landings. She continued to operate in the Philippines until 8 April, when she cleared San Pedro Bay for a stateside overhaul. She returned to Pearl Harbor 22 July, and on 26 August arrived at Okinawa for occupation duty carrying passengers, mail, and light freight between Okinawa and Japan. On 23 October she sailed for Pearl Harbor, San Diego, and Charleston, where she arrived 2 December. After overhaul and a year of inactivity, Coghlan was decommissioned and placed in reserve 31 March 1947.
Coghlan received eight battle stars for World War II service.