Westonbirt School is a co-educational private day and boarding school for pupils aged 11 to 18 near Tetbury in Gloucestershire in South West England. It was set up in 1928 as a girls' school. The historical Westonbirt House is part of the school. Westonbirt Prep School is also on the site.

Westonbirt School was founded by the Martyrs' Memorial and Church of England Trust (now known as the Allied Schools), which had acquired Westonbirt House and converted it into a school. During World War II, the premises were used by the Air Ministry and pupils and staff were evacuated to Wiltshire due to the Blitz. Six former pupils died during the war and a memorial scholarship was set up in their memory; children of British military personnel are entitled to discounts.

In 2002, Westonbirt acquired Querns School to become its preparatory department. Seven years later it absorbed Rose Hill School to form the prep school Rose Hill Westonbirt. In September 2013 Rose Hill Westonbirt School was renamed Westonbirt Prep School. Wishford Education, a provider of independent education in the UK, acquired Westonbirt School in 2018.

As of September 2019, Westonbirt became co-educational and accepted boys into year 7, and in years 8,9 and 12 from September 2020.

Pupils are approximately one-third boarders and two-thirds day girls and boys. All boarders are members of one of the following houses:

Dorchester, named after Dorchester House in London, owned by Robert Stayner Holford, also owner of Westonbirt House, which served as the American Embassy from 1905 and 1912 and was demolished in 1929 to be replaced by the Dorchester luxury hotel. Dorchester dormitories are located in the old servants' quarters at the top of the house, including the school's central tower, currently part of the Dorchester House Mistress' rooms.

Badminton, named after Badminton House with dormitories located in the west wing of the house on the second floor.

Beaufort, named after Beaufort Polo Club.