On 12 July 1940, increased German activity in the English Channel prompted the Royal Navy to transfer her work-ups north to Scapa Flow in the Orkney Islands, and she completed them there later in July 1940 and was assigned to a flotilla based at Sheerness, charged with patrol and convoy defence duties in the English Channel and along the east coast of Great Britain.

[1][2] In May 1941, with her repairs completed, Hambledon passed her post-repair trials and on 14 May 1941 took up convoy escort and anti-invasion patrol duties in the North Sea with the 16th Destroyer Flotilla, based at Harwich, England, which she continued through October 1942.

[3][4] When convoy traffic along the east coast of Great Britain was reduced to free escorts for use elsewhere, Hambledon was selected for detached service in October 1942.

[1] In June 1943, the Royal Navy selected Hambledon for participation in Operation Husky, the Allied invasion of Sicily, and transferred her to the 58th Destroyer Division.

[1] In August 1943, Hambledon was selected to carry Admiral of the Fleet Andrew Cunningham for Operation Avalanche, the Allied landings at Salerno on the mainland of Italy planned for September 1943.

[1][2][5] In April 1944, the Royal Navy selected Hambledon, Blencathra, and Mendip to participate in Operation Neptune, the initial assault phase of the Allied invasion of Normandy scheduled for early June 1944.

The convoy arrived off Gold Beach on 6 June 1944 and put its troops ashore, with Hambledon supporting the landing by bombarding German shore defences.

Later in the day, Hambledon steamed back to the Solent to escort Convoy EBP 2 bringing reinforcements and supplies to the beachhead, fighting an action against German S-boats south of the Isle of Wight along the way.

On 7 June 1944, she joined the 112th Escort Group – made up of the frigates Spragge and Stockham and the sloop Magpie – to escort EBP 2 – five troop transports carrying United States Army troops for discharge on Utah Beach, the headquarters ship for Mulberry B, and three smaller merchant ships – to Utah Beach, where the convoy arrived on 8 June 1944.

In March 1945, she was reassigned to escort convoys crossing the North Sea between the United Kingdom and ports in Belgium and the Netherlands and to patrol duties in the Nore Command and Dover areas.