[4] The destroyer was transferred to the Royal Canadian Navy, into which she was then commissioned and renamed on 21 February 1944 while fitting out at Cowes, and was completed on 5 March 1944.
On 3 April, Sioux escorted the aircraft carriers that attacked the Tirpitz, which was anchored at Altenfjord, Norway, and German shipping along the Norwegian coast as part of Operation Tungsten.
During the assault on Juno Beach, Sioux bombarded shore batteries for forty minutes during the initial landing and provided fire support afterwards.
[7] On 10–11 June, Sioux and the Polish destroyer Krakowiak were sent to intercept a German flotilla of schnellboots laying mines off Le Havre.
[8] On 23 June, the ship bombarded enemy troop concentrations near the mouth of the River Orne and a battery of field guns.
The following day, Sioux and sister ship Algonquin attacked a German battery near Franceville, which was to be their last mission off the coast of Normandy.
[12] On 14–15 October, Sioux escorted a force that was sent to perform air-mining and attacks on Axis shipping routes along the coast of Norway near Frohavet.
[13] The destroyer returned to Norwegian waters from 26–28 October, escorting the aircraft carrier Implacable which attacked targets in Norway as part of Operation Athletic.
[22] After escorting convoy JW 64 to Polyarnoe, Sioux departed on 14 February as part of a relief expedition to convey 500 inhabitants of the Norwegian island of Sørøya, left without food or fishing boats by the Germans, to safety.
[27] The vessel underwent a major refit at Halifax and in November 1945 transferred to the west coast, being paid off on 27 February 1946 at Esquimalt.
[28] In March 1950, with the cruiser Ontario and destroyer Cayuga, Sioux participated in a training cruise to Mexico, making several port visits.
[29] After the declaration of war in Korea, Canada ordered three destroyers of the Pacific Division based at CFB Esquimalt to begin preparations for deployment to the Korean theatre.
Initially retained at Sasebo for rescue missions, on 12 August 1950, the ship transferred to Task Unit 96.53.3 assigned to the west coast of Korea.
However, en route the vessel encountered Typhoon Clara and suffered slight damage that required repairs upon her arrival.
[34] Upon the destroyer's return from Hong Kong she began blockade duties in coastal waters around Inchon and the mouth of the Yalu River, as part of Task Element 95.12 alongside the other Canadian vessels.
[36] Sioux then spent the rest of her time in theatre screening the aircraft carrier, HMS Theseus, escorting shipping, blockade patrol and providing general support for the forces evacuating Inchon.
[3] In 1953 Sioux was one of a number of Royal Canadian Navy ships which took part in the Fleet Review to celebrate the Coronation of Queen Elizabeth II.