HMS Juno was a J-class destroyer of the Royal Navy laid down by the Fairfield Shipbuilding and Engineering Company, Limited, at Govan in Scotland on 5 October 1937, launched on 8 December 1938 and commissioned on 25 August 1939.

The eight ships of the J class were ordered on 25 March 1937, and Juno was laid down with the name Jamaica at Fairfield's Govan shipyard on 5 October 1937.

[8][9] The initial work-up of the ship and her crew was interrupted by the German invasion of Poland on 1 September 1939, and on 6 September 1939, Juno and sister ships Janus and Jackal escorted the Norwegian steamer SS Batavia, carrying the staff of the British embassy in Berlin across the North Sea from Rotterdam to the Tongue lightship in the Thames estuary.

[1] On the night of 6/7 December 1939, Juno and Jersey were on patrol off Cromer when they encountered two German destroyers, Hans Lody and Erich Giese, returning from a minelaying sortie.

Juno in response, searched for a submarine, which was believed to have fired the torpedo, allowing the German destroyers to escape unchallenged.

[14] On 5 April 1940, Juno left Methil together with the destroyers Javelin, Janus and Grenade as escort to the Norway-bound convoy ON.25.