The Southern Department was a former department of the government of England and later the Kingdom of Great Britain. It had a variety of responsibilities, including domestic and Irish policy, colonial policy and foreign affairs concerning southern European powers such as France, Spain, Portugal, Switzerland, Italy and the Ottoman Empire. It was administered by the Secretary of State for the Southern Department.
The Southern Department's opposite number within government was the Northern Department, responsible for government dealings in northern Europe.
In 1782, the Northern and Southern Departments were reorganised, with the Foreign Office taking over their foreign affairs responsibilities and Home Office taking over their domestic affairs responsibilities.