The ship was launched on February 21, 1939, and completed for service on October 1,1940 by which time World War 2 had already been fought for a year. After a trip to the USA, she covered the Lofoten raid (March 1941) and Atlantic convoys before becoming flagship of the British Home Fleet in April 1941. In May 1941 she led the chase of the German Bismarck and saw action for the first time. Through 1941-42 King George V took part in numerous search and escort operations in the Atlantic and in May 1943 she went to the Mediterranean taking part in all the big naval operations covering the Allied invasion of Sicily and Italy. After refitting in England she went East as flagship of the second in command of the British Pacific Fleet. In Task Force 57 (later 37) she was part of the big Anglo-American naval force in the Okinawa operations and operations against Japan. In 1946 she became flagship of the British Home Fleet once more, the war now over, and in 1947-49 she served as a training ship before paying off into the Reserve Fleet in 1950. She was scrapped in 1957 along with her sister ships Howe, Anson, and Duke of York. A further sister ship Prince of Wales was sunk by Japanese forces in 1941.
During her service life King George V underwent minor changes of armament. In 1940 she had four unrating rocket projectors for use against aircraft, but these were soon removed. She later had pom pom armament doubled and many 20 mm Oerlikon guns replaced the 0.5 inch machine guns.