Milton Keynes (England) is founded as a new town by Order in Council, with a planning brief to become a city of 250,000 people. Its initial designated area enclosed three existing towns and twenty-one villages. The area to be developed was largely farmland, with evidence of continuous settlement dating back to the Bronze Age.

Milton Keynes is a city in Buckinghamshire, England, about 50 miles (80 km) north-west of London. At the 2021 Census, the population of its urban area was 264,349. The River Great Ouse forms the northern boundary of the urban area; a tributary, the River Ouzel, meanders through its linear parks and balancing lakes. Approximately 25% of the urban area is parkland or woodland and includes two Sites of Special Scientific Interest (SSSIs). The city is made up of many different districts.

The new towns in the United Kingdom were planned under the powers of the New Towns Act 1946 and later acts to relocate people from poor or bombed-out housing following the Second World War. Designated new towns were placed under the supervision of a development corporation, and were developed in three waves. Later developments included the "expanded towns": existing towns which were substantially expanded to accommodate what was called the "overspill" population from densely populated areas of deprivation.

An Order in Council is a type of legal instrument issued by the executive branch of a government, often the head of state or their representatives, on the advice of a cabinet or council of ministers. These instruments are used in several Commonwealth realms, with equivalent instruments also found in countries with a Westminster system of government. Although the specifics vary by country, Orders in Council typically allow the executive to make formal decisions or regulations without enacting new legislation.

This history of Milton Keynes details its development from the earliest human settlements, through the plans for a 'new city' for 250,000 people in northern Southeast England, its subsequent urban design and development, to the present day. Milton Keynes, founded in 1967, is the largest settlement and only city in Buckinghamshire. At the 2021 census, the population of its urban area was estimated to have exceeded 256,000.