City of Westminster College has its origins in an evening institute established in the First World War providing lip-reading classes for deafened servicemen in the vestry of St George's Church in Hanover Square, Westminster. The institute, which became known as St George's Institute, only ran evening classes and moved to a number of different sites, successively St George's Row School, Ebury Bridge and Dean Farrar Street. A further move was made to the Burdett Cookery School, with some classes held in the Townsend Foundation School, Rochester Row. The institute grew rapidly during the 1930s, becoming one of the largest commercial institutes in London, with classrooms and chemistry laboratories in Westminster City College. In 1936 an arrangement with Westminster Training College was made enabling the institute to provide more student hours than any comparable institute in London and replacing the link with Westminster City College. The institute moved again to the Millbank School, Erasmus Street.
In 1939 two social studies courses were introduced, whilst languages and commercial, administrative and social studies were all well established.The Waterloo Road School site was taken over by the institute in 1951, shared with the Law Department of Kennington College. By 1959 there were 41 full-time staff, more part-time lecturers and over 30 rooms used. Full-time courses were offered in 1959 in the institute's three departments of Civil Service, Commerce and University Entrance, with part-time and evening work. In 1954 the institute moved to Francis House, renting space from the Army and Navy Stores. Further space was rented from them in 1955, enabling matriculation work to be transferred from Regent Street Polytechnic. New departments of Science, Social Studies and Day Release work were created. Awards and courses were rationalised following the 1959 McMeeking report 'Further Education in Commerce', with the introduction of national certificates in business studies, and establishment of new departments of Economics and Arts and Science and Maths. By 1962 there were over 6000 students associated with the institute. In 1965 the work of the Arts Department was transferred to the West London College of Commerce.
In 1959 the institute was renamed City of Westminster College. In the early 1960s the first courses in Hospital Administration were organised, and part of the college moved in 1966 to Blackfriars Road where housing laboratories and the Social Studies Department were accommodated (later to become part of Southwark College). In the mid 1960s new departments of Professional Studies, later renamed Accountancy and Finance, and Business Studies were established. The publication of the White Paper 'A Plan for Polytechnics and Other Colleges', published in 1966, had announced the creation of some 30 polytechnics throughout the country to form what became called the public sector of the binary system of higher education. The 13 existing colleges managed by ILEA were to be reorganised into five. City of Westminster College joined with Borough Polytechnic, the Brixton School of Building, and the National College for Heating, Ventilating, Refrigeration and Fan Engineering to become the Polytechnic of the South Bank in 1970.
The premises were used by the new Polytechnic for a short time after the merger to house the Department of Accountacy and Finance, the Department of Business Studies, the Department of Languages and the Department of Management and Administration.