Vice-Admiral John Hughes-Hallett (December 1901 – 1972) was a British naval commander and politician. He was the Naval Commander during the Dieppe Raid of 1942.

Hughes-Hallett was born in December 1901, to a distinguished armed services family. His father was Colonel Wyndham Hughes-Hallett, his mother Clementina Loch. They were relatively old at 56 and 48 years old respectively at the time of his birth.

Hughes-Hallett had a distinguished service in the Royal Navy beginning as a Midshipman on HMS Lion, May 1918. He rose through the ranks. During World War II he served in a variety of roles. In the Norwegian campaign, 1940, on HMS Devonshire, he was mentioned in despatches.

Hughes-Hallett played an important role in cross-Channel raids. He assisted in planning the raids under Mountbatten and was the Naval Commander during the misconceived Dieppe Raid in 1942. Although the raid itself was not successful and cost many lives, it did lead to new strategies for cross-Channel operations. The actual proposer of the idea of the Mulberry Harbour is disputed, but it is believed by some to have been Hughes-Hallett. At a meeting following the Dieppe raid he declared that if a port could not be captured, then one should be taken across the Channel. Although this was met with derision at the time, the concept of Mulberry Harbours began to take shape when Hughes-Hallett moved to be Naval Chief of Staff to the Overlord planners.

Hughes-Hallett became Commodore commanding the Channel Assault Force and Naval Chief of Staff (X) from 1942 to 1943. Of the five Assault Forces, Hughes-Hallett ‘s Force "J" started its training with a decided advantage over the other four, its nucleus having been formed as far back as October 1942, with headquarters at Cowes. On 1 May 1943, Commodore Hughes-Hallett succeeded Rear Admiral Vian as the head of the Naval Branch at Supreme Allied Command. He served as Captain of HMS Jamaica from December 1943. After the war, he was in command of HMS Vernon, (1946-8) and of HMS Illustrious, (1948-9). He became Vice-Controller of the Navy, 1950-2, and Flag Officer, Heavy Squadron, Home Fleet, 1952-3.

Hughes-Hallett retired from the navy in 1954 as Vice-Admiral on his adoption as a Conservative Parliamentary candidate. First elected in September 1954, he served as the Member of Parliament for East, later North East, Croydon until the 1964 election. He was a British Representative at the Council of Europe between 1958 and 1960 and Parliamentary Secretary to the Ministry of Transport for Shipping and Shipbuilding, 1961 to 1964. In the 1958/59 parliament, he successfully piloted his private members bill through parliament, although only tenth in the ballot. It became the Road Traffic (Driving of Motor Cycles) Act.

Hughes-Hallett lived in Slindon, near Arundel, Sussex, England and died in 1972. His brother, Sir (Cecil) Charles Hughes-Hallett was a Rear Admiral. He had drafted memoirs but they have not as yet been published.