The Foreign Office was established on 27 March 1782, when Britain's Secretary of State for the Northern Department became Secretary of State for Foreign Affairs and his secretariat officially became known as the Foreign Office. The department took on the government's foreign affairs functions. Domestic affairs became the responsibility of the Home Office.

On 17 October 1968, the Foreign and Commonwealth Office (FCO) was created when the Foreign Office (FO) merged with the Commonwealth Office and the Diplomatic Service Administration Office.