Joining the Pacific Fleet in late 1937, Mugford conducted local operations along the West Coast and around the Hawaiian Islands, taking time out for periodic overhauls and upkeep.

When the attack began, Mugford was on standby status, berthed at B6 in the Navy Yard for repairs, and while raising steam to get underway, downed three planes in 10 minutes with her antiaircraft guns.

On the 9th, she sped toward the action of the first Battle of Savo Island, arriving in time to pull 400 survivors of Vincennes (CA-44) and Astoria (CA-34) from the water.

After battle damage repairs at Sydney, from 16 September through December, she operated on patrol in the Coral Sea and along Australia’s northern coast.

After repairs at Milne Bay, Mugford returned to patrol, bombardment, and escort missions for the New Guinea operation, sailing off Saidor.

Mugford returned to Pearl Harbor 10 May for training in preparation for the Marianas operation, for which she staged at Majuro.

On 5 December, Mugford spotted enemy aircraft attacking amphibious craft passing through her patrol area in Surigao Strait.

Returning to the western Pacific in mid‑March, Mugford served as radar picket and on antisubmarine patrol between Ulithi and Saipan until the close of the war.

She served in TG 55.7 repatriating Allied prisoners of war from Japan to Okinawa early in September, then screened carriers providing air support for the occupation of the Nagasaki‑Sasebo area.