Saint Marylebone School is a comprehensive secondary school in Marylebone, London. It specialises in Performing Arts, General Arts, Maths & Computing. In the sixth form, boys can attend as well. The school then became a converter academy, having previously been judged as "outstanding in every respect" by Ofsted.

Founded in 1791, Saint Marylebone Church of England School is now a multi-faith comprehensive school. The main site is located just behind St Marylebone Parish Church, with the Sixth Form Centre based in another building nearby at Blandford Street.

The St Marylebone School began as the Marylebone "Day School of Industry," founded in 1791 in what was then Paradise Street, now Moxon Street, to educate the children of the poor in the parish. Boys and girls were taught skills such as needlework and straw plaiting. The school was funded by donations, charity sermons and income from the children's handiwork. In 1808, with the support of local philanthropist and social reformer Sir Thomas Bernard, the school moved to 82 Marylebone High Street, which is now a boutique store. Subsequently, to make room for growing numbers, it moved to a site on Paddington Street, which is identifiable today as a Mission Church. Then in 1858 the 5th Duke of Portland bought a plot of ground near the top of Marylebone High Street and covenanted the site to be used for a girls' school in perpetuity. The main site of the school has been there ever since.

The Day British School of Industry had been incorporated with Sir Thomas Bernard's school under the direction of the Governor of the Church of England's United National Schools. In 1858, it became known as Central National School, to distinguish it from the Eastern (now All Souls CE Primary) and Western National Schools (now St Mary's Bryanston Square CE Primary) founded in 1824 at nearby parishes.

The boys' section was eventually closed in November 2022 and it became a girls' school, adopting its current name. In the 1960s-70s the school used a building in Penfold Street, about 15 minutes from the main site, for domestic science lessons; this building is now used by the Westminster Youth Service. In 2005, the sixth form moved to part of a building that had housed a convent; in 2008-9 this was demolished and rebuilt as a five-story, university-style Sixth Form Centre.

During the school's grant-maintained period, it was highly selective and the school used to interview parents and prospective pupils.

Between 2005 and 2010, the main site saw extensive building and refurbishment work. Major new facilities were opened in 2007, including a below-ground gymnasium and dance studios as well as a music recording studio space and a three-story visual and performing arts space. Since 2013, the school's studio has been the main filming spot for Spirit Young Performers Company. Popular videos shot at this location include "Little Miss High and Mighty" and "Hard Knock Life".

Historically, the school had four houses - Dickens, Barret, Hardwick and Wesley. In September 2010, a fifth house, Nightingale, was added and, in September 2017, a sixth house was named after Ada Lovelace. The houses are named after these significant people as they have had some kind of connection with the school (e.g. Thomas Hardwick designed the St Marylebone Church). Dickens's house has been renamed 'Dove' after Evelyn Dove who studied at the Royal Academy of Music which is located close to the school. The houses have the following colours: blue (Barret), yellow (Dove), red (Hardwick), green (Wesley), purple (Nightingale) and orange (Ada). When joining the school, pupils are assigned to one of the houses.