When the Second World War began in 1939, the Royal Navy decided to reconvert her back into a heavy cruiser, but the work was repeatedly delayed by higher-priority repairs for other ships and she did not reenter service until early 1942.

She returned to the UK in early 1944 to participate in Operation Neptune, the naval portion of the invasion of Normandy in June.

The Hawkins-class cruisers were designed to be able to hunt down commerce raiders in the open ocean, for which they needed a heavy armament, high speed and long range.

[6] The ships were originally designed with 60,000-shaft-horsepower (45,000 kW) propulsion machinery, but the Admiralty decided in 1917 to replace their four coal-fired boilers with more powerful oil-burning ones.

[7] Frobisher carried 2,186 long tons (2,221 t) of fuel oil to give her a range of 5,640 nautical miles (10,450 km; 6,490 mi) at 10 knots (19 km/h; 12 mph).

It used data provided by the 15-foot (4.6 m) coincidence rangefinder in the gunnery director positioned under the spotting top at the head of the tripod mast.

[11] The ship was ordered in December 1915, laid down by HM Dockyard, Devonport on 2 August 1916, launched on 20 March 1920 and completed on 20 September 1924.

The squadron was temporarily deployed to the China Station before Boyle relinquished command[14] on 10 September 1928 to Rear-Admiral Henry Parker.

[16] In 1927–1928 Frobisher was briefly fitted with a prototype F.I.H aircraft catapult and a crane on the quarterdeck, displacing the four-inch AA gun.

[12] By June 1930 her aft superfiring gun had been removed to provide space for a floatplane and her superstructure was built up around the base of the mainmast.

[25] On 6 June Frobisher was assigned to Gunfire Bombardment Support Force D which initially targeted the defenses at Sword Beach during the D-Day landings.

The ship is known to have bombarded the coastal artillery position at Riva-Bella in Ouistreham[26] and to have knocked out the fire-control observation post in the town proper with a direct hit.

[28] In August, she and the repair ship Albatross were damaged by long-range G7e Dackel torpedoes fired from E-boats in the Baie de la Seine.

[29] While Frobisher was under repair at HM Dockyard, Chatham, the Royal Navy decided to reconvert her into a training ship for 150 cadets.

She was sold for scrap to John Cashmore Ltd on 26 March 1949 and arrived at their facility in Newport, Wales, to be broken up on 11 May of that year.