During the Spanish Civil War of 1936–1939, the ship enforced the arms blockade imposed by Britain and France on both sides as part of the Mediterranean Fleet.

During the first few months of the Second World War, Havock searched for German commerce raiders in the Atlantic Ocean and participated in the First Battle of Narvik during the Norwegian Campaign of April–June 1940 before she was transferred back to the Mediterranean Fleet in May where she escorted a number of convoys to Malta.

On 6 April, while on passage to Gibraltar, Havock ran aground near Cape Bon, Tunisia, and her crew was interned by the Vichy French at Laghouat in the Sahara.

Havock carried a maximum of 470 long tons (480 t) of fuel oil that gave her a range of 5,530 nautical miles (10,240 km; 6,360 mi) at 15 knots (28 km/h; 17 mph).

[4] Most ships of Havock's class had the rear torpedo tubes replaced by a 12-pounder AA gun after the evacuation of Dunkirk in 1940, but it is not clear if she received this modification.

On the night of 31 August/1 September 1937, she was unsuccessfully attacked by the Italian submarine Iride with torpedoes, between the Gulf of Valencia and the Balearic Islands.

The ship was refitted in Gibraltar between 19 October and 13 November and required repairs between 16 April and 6 May 1938 after hitting the stone side of a quay.

The mines were laid on the early morning of 8 April, before the Germans began their invasion, and the destroyers joined the battlecruiser Renown and her escorts.

The flotilla leader Hardy led four of her half-sisters down Ofotfjord in a surprise dawn attack on Narvik harbour during a blinding snowstorm.

[10] Havock was assigned to the Nore Command shortly afterwards and bombarded German troops occupying Waalhaven Airfield on 10 May together with her sister Hyperion.

She rescued survivors from the sunken ferry Prinses Juliana off the Dutch coast and returned them to the Hook of Holland where she recovered a number of British demolition parties.

Havock and her sister Hasty surprised the Italian submarine Berillo on the surface on 2 October off the coast of Egypt and forced her to scuttle herself.

[14] The ship evacuated Commonwealth troops from Greece at the end of April and was one of three destroyers escorting the light cruiser Ajax when they bombarded Benghazi on the night of 7/8 May.

[13] On 22 March 1942, several splinters from a 15-inch (38 cm) near miss from the Italian battleship Littorio perforated one of her boilers during the Second Battle of Sirte, killing eight men.

[20] Whilst in dock, the ship was a target for Axis aircraft and sustained some damage on 3 April and was ordered to Gibraltar before her repairs were complete.