The Secretary of State for the Southern Department was a position in the cabinet of the government of Kingdom of Great Britain up to 1782, when the Southern Department became the Foreign Office.
Before 1782, the responsibilities of the two British Secretaries of State for the Northern and the Southern departments were divided not based on the principles of modern ministerial divisions, but geographically. The Secretary of State for the Southern Department, the more senior, was responsible for Southern England, Wales, Ireland, the American colonies (until 1768 when the charge was given to the Secretary of State for the Colonies), and relations with the Roman Catholic and Muslim states of Europe. The Secretary of State for the Northern Department, the more junior, was responsible for Northern England, Scotland, and relations with the Protestant states of northern Europe.
In 1782, the two Secretaries of State were reformed as the Secretary of State for the Home Department and the Secretary of State for Foreign Affairs.