Oswald Tuck was born in 1876, the youngest of 8 children born to Henry Barber Tuck, and his wife Harriott Tuck [née Hozin]. He was educated at Greenwich Hospital School. He married Florence Jane Peglar [also known as Peggy], in 1912; they had two children, Margaret and Sylvia.

His career began at the Royal Observatory in Greenwich, 1892-6. He then entered the Royal Navy, 1896, to teach astronomy and navigation on the training ship HMS Conway on the River Mersey. He was appointed a Naval Instructor, 1899, and sent to East Asia, where he served first in HMS Goliath and later in HMS King Alfred, 1900-9. He began to learn Japanese, 1901-2, during two periods of leave spent travelling around Japan and, in 1902, he took on a Japanese servant, Takego, with whom he continued to practise the spoken and written language. He took two months' home leave, 1903, and rejoined HMS King Alfred, 1903-4. He followed an official course of study in Japanese, 1905, and lived ashore in Japan. He was appointed Japanese Interpreter to HMS King Alfred and authorised to teach Japanese to fellow naval officers, 1906-7. He also took on translation work and acted as an interpreter for the Admiral, making speeches for him on official occasions. He lived ashore again, 1907, and began his translation of the secret Japanese naval history of the Russo-Japanese War, assisted by a student, Jitsuzo. He was appointed Assistant to the Naval Attaché in Tokyo, 1908-9.

He returned to the Admiralty in London, 1909, and continued his translation of the secret history, working as an assistant to the naval historian Julian Corbett. He served in Naval Intelligence, 1914-18, and, after the war ended, was appointed archivist in the Historical Section of the Admiralty, retiring as head of the section, 1937. During this period, he assembled documents and wrote up the naval history of the First World War and continued to translate, lecture and advise on the Japanese language. During the 1930s Tuck also worked for the BBC as a Bible reader, and took a keen interest in drama, writing and directing local amateur plays.

He moved to the Ministry of Information and became a Press Censor in Japanese, 1939-41, where he worked on vetting journalists' reports. On the declaration of war with Japan, he was recalled by the Admiralty to teach intensive six-month courses in Japanese to students recruited to decrypt Japanese military cyphers at Bletchley Park, 1942-5. He was based at the Bedford Japanese School, at first above a gas showroom in Ardour House and then in a succession of houses around the town. The courses were a great success and students learnt Japanese in a far shorter time than had been previously thought possible. After the war, he continued teaching Japanese and translating at the Royal Naval College, Greenwich, 1946.

He died on 26 February 1950; his wife died 6 years later.