During the Second World War she reverted to her designed role, serving in home waters on patrol and convoy escort duties.

In early 1940 Codrington played a minor role during the Norwegian campaign and then the German invasion of France and the Low Countries in May.

[1] As a flotilla leader the ship was almost 200 long tons (200 t) larger than the other A-class destroyers because she carried more guns and her bridge structure had to be enlarged to provide the additional accommodation required for the Captain (D) and his staff.

[4] Codrington carried a maximum of 430 long tons (440 t) of fuel oil that gave her a range of 4,800 nautical miles (8,900 km; 5,500 mi) at 15 knots (28 km/h; 17 mph).

[7] It is unknown if the flotilla leader's depth-charge equipment changed after the beginning of the war but her stock of depth charges gradually increased.

[14][11] On 23 August, Codrington went to the aid of the British steamer Gibel Jerom (operated by the Bland Line), which had been stopped by the Spanish Republican light cruiser Miguel de Cervantes off Cape Tres Forcas while bound for Nationalist-held Melilla with a cargo of petrol.

Codrington's commanding officer warned the captain of Miguel de Cervantes that Britain would not tolerate any interference with British shipping outside the three-mile limit.

Codrington embarked King George VI on 4 December and transported him to Boulogne for his visit to the British Expeditionary Force in France.

[11] 1940 saw Codrington continue to host VIPs, as on 4 January, she embarked Winston Churchill (then First Lord of the Admiralty) on a visit to France.

[11] On completion of the refit, she joined the flotilla at Harwich on 6 March and resumed convoy defence and patrol duties in the North Sea.

[11] Receiving word that the Royal Air Force had attacked north-bound German warships in the North Sea on 7 April, the fleet, consisting of Codrington, the destroyers Griffin, Jupiter, Electra, Escapade, Brazen, Bedouin, Punjabi, Eskimo and Kimberley formed a screen for the battleships Ramillies and Valiant, the battlecruiser Repulse, the light cruisers Sheffield, Penelope and the French Émile Bertin.

[25] She was back in action on 14 April, being deployed with the destroyers Acasta and Ardent as part of the screen for Valiant which was escorting Convoy NP1 transporting troops and stores for the planned landings in Norway.

[28] She was part of the escort for Convoy FP2 from Scapa Flow to Harstad which conveyed the French 27e Demi-Brigade de Chasseurs Alpins (27th Half-Brigade of Mountain Infantry) from 24 to 27 April.

[29] The following day, the ship embarked Admiral of the Fleet, the Earl of Cork and Orrery and the French General Antoine Béthouart.

[30] When the Germans invaded France and the Low Countries on 10 May, Codrington was transferred back to England, arriving at Dover the following day.

[11] With the destroyer Jaguar, Codrington covered an unsuccessful attempt to cut the underwater telephone cable between Amsterdam and England between 22 and 24 May.

[35][36] In July Codrington was still the leader for the 1st Destroyer Flotilla which was based at Dover for convoy defence and patrol duties in the English Channel.

The destroyer was near-missed by a bomb but the subsequent detonation broke her back and riddled her hull with holes; only three men were wounded in the explosion.

The discovery of four feet (1.2 m) of mud in the boiler room and the torn and twisted pipework therein greatly slowed progress, enough so that the Admiralty cancelled the contract on 30 October and took over the task.