The Royal Borough of Windsor and Maidenhead is a Royal Borough and unitary authority in Berkshire, South East England. While it is named after both the towns of Maidenhead and Windsor, the borough also covers the nearby towns of Ascot and Eton. It is home to Windsor Castle, Eton College, Legoland Windsor and Ascot Racecourse. It is one of four boroughs entitled to be prefixed Royal and is one of six unitary authorities in the county, which has historic and ceremonial status.

The borough was formed on 1 April 1974 as one of six standard districts or boroughs within Berkshire, under the Local Government Act 1972, from minor parts of Berkshire and Buckinghamshire which remained for more than two decades Administrative Counties, and such that Berkshire assumed the high-level local government functions for the resultant area. The change merged the boroughs of Maidenhead and Windsor (formally the Royal Borough of New Windsor), the rural districts of Cookham and Windsor, and in Buckinghamshire, north of the River Thames (on the left bank): Eton urban district and the parishes of Datchet, Horton and Wraysbury in its rural district.^[3] The area immediately inherited by law royal borough status from the town of Windsor which contains Windsor Castle.

The local authority is its Council. Its area became a unitary authority area on 1 April 1998 with virtually full local government powers as Berkshire County Council was abolished.^[4] A minority of the area in terms of population has a lower level of local government, the civil parish.

The borough straddles the River Thames. Approximately half of its flow through the borough has a bypass and seasonally-variable flood relief channel, the Jubilee River. Further flood relief channels are planned for the reaches below the Borough to benefit many other settlements including Datchet and Wraysbury in the borough which were the settlements most widely affected by the UK storms of January-February 2014.^[5]

The Royal Borough of Windsor and Maidenhead contains the following towns and villages:

The Windsor and Maidenhead LEA provides a comprehensive system, with a three-tier successive school system in Windsor, and two-tier education elsewhere. Colleges and sixth forms are available in the main two towns as well as across its borders in Egham, Slough and Wokingham.^[14]

The following people and military units have received the Freedom of the Borough of Windsor and Maidenhead.

This list is incomplete; you can help by adding missing items. (May 2019)

The Royal Borough of Windsor and Maidenhead is twinned with the following Towns:

• Neuilly-sur-Seine, France – established 1955 with Royal Borough of New Windsor.^[17]
• Saint-Cloud, France – established 1957 with Maidenhead.
• Bad Godesberg, Germany – established 1960 with Maidenhead.
• Goslar, Germany – established 1969 with Royal Borough of New Windsor.
• Frascati, Italy – established 1972 with Maidenhead.
• Kortrijk, Belgium – established 1981 with Royal Borough of Windsor and Maidenhead.