The Royal Archives, also known as the King's or Queen's Archives, is a division of the Royal Household of the Sovereign of the United Kingdom. It is operationally under the control of the Keeper of the Royal Archives, who is customarily the Private Secretary to the Sovereign. Although sovereigns have kept records for centuries, the Royal Archives was formally established as recently as 1912 and occupies part of the Round Tower of Windsor Castle.

Since the Royal Archives are privately owned, requests for public access must be approved based on the needs and qualifications of the researcher. The restrictions on access to the archives have attracted criticism from historians and academics and accusations of censorship.

Following Queen Victoria's death in 1901, an appointment for Keeper of the Royal Archives was made by Edward VII to safeguard the Queen's "collection of official and private correspondence". At the behest of George V, this archive along with other royal collections were relocated for storage and display within the Round Tower of Windsor Castle in 1914. Through the attainment of additional records and collections through various means of acquisition, the Royal Archives gradually increased in scale. The tower's renovation and subsequent expansion decades later successfully addressed spatial constraints and provided more effective methods of archival preservation.

The King's Archives is the responsibility of the Assistant Keeper of the King's Archives (also the Royal Librarian), and professional staff under the Archives Services Manager who is in charge of the day-to-day work in the archives. There are several qualified Archivists, as well as a small clerical staff. In addition to paid staff, volunteers are crucial in maintaining collections, developing exhibitions, and facilitating research. Benefiting from the use of the Collections Management System, CALM, Royal Archives staff ensure that collections in the royal archives are efficiently catalogued and made accessible digitally.

Sir John Wheeler-Bennett was Historical Adviser to the Queen's Archives from 1959 to 1975.

Comprising collections including diaries, letters, household papers. and administrative records, the Royal Archives retain significant personal and official information about the British monarchy (also Monarchy of the United Kingdom). The Royal Photograph Collection also occupies part of the Round Tower and holds over 400 000 items of photographic material from the Royal Collection. The Royal Photograph Collection is managed separately from the Royal Archives and is the responsibility of the Head Curator of the Photograph Collection, who reports to the Director of the Royal Collection.

Twentieth century royals including Edward VII, George V, Edward VIII, and George VI are well represented in the Royal Archives. Documents ranging from private correspondence to official government papers illustrate public engagement and diplomacy. Recent files and those currently in use are retained at Buckingham Palace.

In commemoration of the Royal Archives’ foundation, “Treasures from the Royal Archives” was published in 2014 and highlighted several noteworthy collections such as the Georgian Papers and the Letters of Queen Victoria.