She sailed on 5 December 1948 for her first deployment to the Far East, arriving at Tsingtao on 1 January 1949 for operations supporting the Marines ashore in China.

Departing 24 May 1949, John W. Thomason returned via Okinawa to San Diego on 23 June 1949 and spent the remainder of the year training.

During this critical post-war period, she operated with British ships on training maneuvers off the coast of Indochina and Korea, returning to San Diego 25 April 1950.

Under the command of Gordon Chung-Hoon, John W. Thomason sailed on 30 September to join the 7th Fleet, operating in the screen of carrier task groups attacking enemy positions and supply lines.

Antisubmarine exercises took her to Pearl Harbor from January–March 1951, but John W. Thomason arrived off Korea again on 26 March to operate with Boxer and Princeton during air strikes.

Back at Songjin and Wonsan on 26 April, the ship screened larger units, took part in shore bombardment, and patrolled offshore.

John W. Thomason arrived at Wonsan harbor on 2 July; while firing at shore targets five days later, she received numerous shrapnel hits in a duel with enemy batteries.

[1] In March 1959, John W. Thomason entered Long Beach Naval Shipyard as the prototype ship for the new Fleet Rehabilitation and Modernization (FRAM) program.

During this extensive repair and modernization period she received a helicopter deck and hangar aft, variable depth sonar, the latest electronic equipment, and many improvements in living and working spaces.

During the cruise which followed, the ship trained in her antisubmarine warfare (ASW) tactics and became familiar with her new equipment in operations with 7th Fleet and the Japanese Maritime Self-Defense Force.

Exactly a month later, with four other destroyers, she got under way for the western Pacific screening Yorktown and arrived at Yokosuka, Japan on 4 December, joining the 7th Fleet.

[1] After returning to the West Coast, she departed San Diego for the Far East 22 March 1966 and reached Da Nang 19 April and the same day took station a few miles south of Chu Lai.

After visiting Guam and Japan, John W. Thomason headed home on 9 September, reached San Diego on 24 August and operated off the West Coast into 1967.

After several days along the coast, the destroyer navigated the Nha Be River to participate in gunfire support in the Rung Sat Special Zone.

John W. Thomason escorted Hancock to Subic Bay and back to Yankee Station before rejoining Bon Homme Richard in this last line period.