Cornwall Terrace (also 1-21 Cornwall Terrace) is a Grade I listed building of consecutive terraced mansions overlooking Regent's Park in the City of Westminster, London, England. It is situated at The Park's southwest corner, near Baker Street, between York Terrace and Clarence Terrace, within the park's Crown Estate development. Cornwall Terrace was part of the scheme of the Prince Regent, later King George IV, to develop grand housing in Regent's Park.
Cornwall Terrace was one of the earliest buildings constructed in Regency Park, and the park's first completed terrace. Construction occurred between 1821 and 1823 by the builder and developer, James Burton. The design was by his son, Decimus Burton, though Sir John Nash was responsible for the main lines, Greco-Roman in style, and supervised construction. After the Second World War, the terrace was refurbished. It became a Grade I listed building on 9 January 1970.