Haydon School is a mixed secondary school and sixth form in the Northwood Hills area of the London Borough of Hillingdon, Greater London, for students aged 11 to 18. On 1 April 2011, Haydon School became an Academy.

The school was formed in September 1977 from the union of St Nicholas Grammar School and St Mary's Grammar School for Girls.^{[citation needed]}

It was named after the local family, as was Haydon Hall. Alice Spencer, Countess of Derby, had the hall built in 1630.

Haydon was a designated language college teaching students foreign languages.^{[citation needed]}

At GCSE-Level, the school offers Latin and community languages as well as: Arabic, Bengali, Greek, Gujarati, Hebrew, Hindi, Punjabi, Persian, Polish, Portuguese, Russian, Turkish, Urdu^{[citation needed]}

The Dobson Library was opened in 1996 and named after the retiring headteacher - David Dobson.

The Peter Woods building was opened on Thursday 9 July 2009 by former headmaster and namesake Peter Woods.^{[citation needed]}

Haydon School has over 500 students in its sixth form. It offers advanced level courses on site.