After shakedown along the California coast, Gwin sailed for the Pacific theatre as flagship of Mine Squadron 3, reaching Pearl Harbor 3 January 1945.

Acting in a variety of roles—antisubmarine screen, radar picket ship, minesweeper, fire support—Gwin was to remain off Okinawa the following five months, almost to the very end of the war.

Then, as damage control parties rushed to quell the fires raging around the kamikaze, the Japanese attack ended as suddenly as it had begun.

After a brief stay at Ryukyu Islands for battle damage repairs, Gwin returned to patrol and sweeping duties around Okinawa.

With her share of the Pacific "mopping-up" complete, Gwin at last headed home, reaching San Pedro, Los Angeles on 23 February 1946.

In 1953 Gwin crossed the Atlantic for a 4-month tour of duty with the 6th Fleet, visiting ten Mediterranean ports before returning to Charleston 3 February 1954.

Gwin returned to the Mediterranean a final time in 1957 for NATO maneuvers with ships of the Portuguese, French, and British navies, visiting both Brest and Gibraltar.

In between Caribbean and Mediterranean cruises and training, Gwin engaged in a variety of minesweeping and hunter-killer antisubmarine exercises along the East Coast and participated in several other NATO maneuvers in American waters.