The first two Town-class were ordered from Vickers Armstrong and John Brown & Company on 1 June 1934 as part of the 1933 Construction Programme for the Royal Navy.

[1] Newcastle was launched, in a low-key ceremony owing to the death of King George V three days earlier, on 23 January 1936 by the Duchess of Northumberland.

[11][12] On 25–26 September 1939, Newcastle sailed with the Home Fleet as it sortied to cover the 2nd Cruiser Squadron which was escorting the submarine Spearfish, which had been damaged by German trawlers, back to Britain.

[15] On 23 November 1939, the German battleships Scharnhorst and Gneisenau, on a sortie into the North Atlantic, encountered and quickly sank the British armed merchant cruiser Rawalpindi of the Northern Patrol.

[18] On the night of 10/11 October 1940, Newcastle provided illumination with star shells while the battleship Revenge bombarded the French port of Cherbourg in an attempt to destroy shipping that could be used in a German invasion.

Later that day, the British force encountered the German destroyers Hans Lody, Friedrich Ihn, Erich Steinbrinck and Karl Galster.

[15][21][22] Newcastle was then ordered to the South Atlantic, taking part in an unsuccessful search for the German auxiliary cruiser Thor that month.

[28][11][18] After work up at Scapa Flow, Newcastle left to rejoin the Eastern Fleet on 15 April 1943, arriving at Kilindini Harbour in Kenya on 27 May, where she resumed her role as the flagship of the 4th Cruiser Squadron.

[32] In February 1944, Newcastle, together with Relentless and Catalina flying boats, were deployed in a search for the U-boat supply ship Charlotte Schliemann based on intelligence from decrypted radio messages.

[33][34] On 12 March 1944, Newcastle together with the escort carrier, Battler, the cruiser Sussex and the destroyers Roebuck and Quadrant, were sent to intercept the U-boat supply ship Brake, again in response to signals intelligence.

[40] On 26 January, Newcastle, together with the cruisers Nigeria and Kenya and the destroyers Paladin and Rapid, landed Royal Marines on Cheduba Island.

[18] Newcastle completed the refit in October 1945,[18] and was then used as a troopship carrying out trips to South Africa and Colombo, Ceylon before entering reserve at Devonport in February 1946.

[44] In May 1952, Newcastle left British waters to serve in the Korean War,[42] relieving the cruiser Ceylon on station off Korea on 4 July that year.