The sister ships spent most of their careers assigned to the 2nd Battle Squadron of the Home and Grand Fleets, sometimes serving as flagships.

The three surviving ships were briefly reduced to reserve in 1919 before being transferred to the Mediterranean Fleet in 1920–1921 where they played minor roles in the Allied intervention in the Russian Civil War and the Chanak Crisis of 1922.

The imminent completion of the two Nelson-class battleships in 1927 forced the sale of King George V and Ajax for scrap at the end of 1926 while Centurion was converted into a target ship to comply with the tonnage limitations of the Washington Naval Treaty.

During the Second World War, Centurion was rearmed with light weapons and was converted into a blockship and was then modified into a decoy with dummy gun turrets.

[2] Sea trials with the battlecruiser Lion showed that the placement of the fore funnel between the forward superstructure and the foremast meant that hot clinkers and flue gases from the boilers made the spotting top on the foremast completely unworkable when the forward boilers were alight and that the upper bridge could easily be rendered uninhabitable, depending on the wind.

[4] The King George V class was equipped with ten 45-calibre breech-loading (BL) 13.5-inch Mark V gun in five hydraulically powered, centreline, twin-gun turrets, designated 'A', 'B', 'Q', 'X' and 'Y' from front to rear.

[2] Training exercises had shown that destroyer and torpedo boats attacked more frequently from the frontal arc, so the sixteen 50-calibre BL four-inch (100 mm) Mark VII guns of the secondary armament was re-arranged to improve fire distribution ahead.

[2] The ships of the King George V class were some of the first battleships in the RN to receive the full suite of fire-control equipment used during the First World War.

Data from a 9-foot (2.7 m) coincidence rangefinder (an unstabilized Barr and Stroud instrument in King George V and stabilized Argo units in the other ships) on the roof of the conning tower, together with the target's speed and course information, was input into a Dumaresq mechanical computer and electrically transmitted to a Dreyer Fire-control Table (a Mark III system in King George V and Mark II Tables in the others with an Argo range clock replacing the Dreyer-Elphinstone model in the Mark III) located in the transmitting station located on the main deck.

[10][11] The King George Vs had a waterline belt of Krupp cemented armour that was 12 inches (305 mm) thick between the fore and rear barbettes.

Unlike the Orions, the anti-torpedo bulkheads were extended to cover the engine rooms, as well as the magazines with thicknesses ranging from 1 to 1.75 inches (25 to 44 mm).

About 80 long tons (81 t) of additional deck armour was added after the Battle of Jutland in May 1916 and King George V was fitted to tow kite balloons around the same time.

The stern torpedo tube was removed during 1917–1918 and one or two flying-off platforms were fitted aboard each ship in 1918; these were mounted on turret roofs and extended onto the gun barrels.

[13] While conducting her sea trials on the night of 9/10 December, Centurion accidentally rammed and sank the Italian steamer SS Derna and she was under repair until March 1913.

[19] While the 2nd Battle Squadron was conducting gunnery training off the northern coast of Ireland on 27 October, Audacious struck a mine and sank; all of her crew was successfully rescued before she capsized.

They mustered the six dreadnoughts of the 2nd Battle Squadron, including the three surviving King George Vs, and the four battlecruisers of Vice-Admiral Sir David Beatty.

The Germans got the better of the initial exchange of fire, severely damaging several British destroyers, but Admiral Friedrich von Ingenohl, commander of the High Seas Fleet, ordered his ships to turn away, concerned about the possibility of a massed attack by British destroyers in the dawn's light.

[24] Once Jellicoe's ships had rendezvoused with the 2nd Battle Squadron, coming from Cromarty, Scotland, on the morning of 31 May, he organised the main body of the Grand Fleet in parallel columns of divisions of four dreadnoughts each.

[25] The sisters were able to fire a few volleys at the battlecruisers of the I Scouting Group without effect early in the battle, but the manoeuvers of their escorting light cruisers frequently blocked their views of the German ships.

King George V was the first of the trio to return home in early 1923 and she served a training ship until she was sold for scrap at the end of 1926.

[17][29] The British tonnage allowance granted by the Washington Naval Treaty permitted them to keep the three sisters in service until the two Nelson-class battleships were completed in 1927.

[30] While King George V and Ajax were scrapped, Centurion was demilitarized by the removal of her armament and was converted into a radio-controlled target ship.

In preparation for that operation (subsequently cancelled), she was modified into a decoy with dummy gun turrets in an attempt to fool the Axis powers.

[34] The ship was scuttled off Omaha Beach in June 1944 to form a breakwater to protect a mulberry harbour built to supply the forces ashore.