Gridley fitted out at Boston Navy Yard, and conducted shakedown in the Caribbean area until 27 October 1938, visiting Puerto Rico, Cuba, and Venezuela.

She then underwent alterations at the Boston Navy Yard until 13 June 1938, when she departed that port, transited the Panama Canal, and entered San Diego harbor 5 July 1938.

The Task Force was approaching that base on the morning of 7 December when the message heralding the beginning of the war was received: "Air raid on Pearl Harbor, this is no drill."

Departing Dutch Harbor 25 September 1942, Gridley joined the Saratoga task force in Hawaiian waters and later performed escort missions for both combatant and non-combatant ships in the Fijis and New Hebrides.

Vice Admiral Marc A. Mitscher's Carrier Task Force 58 departed Pearl Harbor 18 January 1944 for the offensive in the Marshall Islands, with Gridley again acting as screening ship for Saratoga.

Gridley was with American forces in the pivotal Battle of the Philippine Sea 19 to 20 June 1944, when four waves of Japanese torpedo bombers and escorting fighters were decimated by fleet air and surface units.

While protecting the large ships off Luzon 28 October 1944 she and destroyer Helm detected and sank the Japanese submarine I-51 with a series of devastating depth charge attacks.

After stopping again at Ulithi, Gridley escorted battleship Mississippi en route to Pearl Harbor, and then sailed via San Diego and the Panama Canal for New York, where she arrived 30 March 1945.