The City of Norwich School, more commonly known as CNS, is a coeducational secondary school and sixth form with academy status in Norwich, England.

In 1910, the Education Committee decided to merge the King Edward VI Middle School in Norwich with the Municipal and Presbyterian Schools for boys to create the new City of Norwich School, a boys' grammar school, which was to be built at Eaton

It had around 950 boys in 1960, and around 850 in 1969 when administered by the Norwich Education Committee.

It became a comprehensive in 1970 at which point its name changed to Eaton (City of Norwich) School and co-educational in 1971. Three female sixth-formers were admitted in 1972 (Hazel, Marian and Mary.) The school was refurbished in 2007. The Arc is a new building, as is the Skinner Centre.

Previously a community school administered by Norfolk County Council, City of Norwich School converted to academy status on 1 September 2014 and is now sponsored by Ormiston Academies Trust. However the school continues to co-ordinate with Norfolk County Council for admissions.

The pupils at CNS are split into five houses named after famous beaches in Norfolk: Blakeney, Holkham, Kelling, Thornham and Winterton. Their house colours are Blue, Purple, Green, Yellow and Red respectively.

CNS Charities Week is a week usually the last school week before Christmas where the pupils and members of staff attempt to raise as much money as possible for a charity of the school's choice. The week involves fund raising activities such as Total Wipeout, The X Factor, a teacher auction and CNS Got Talent.