The Secretary of State for Commonwealth Affairs was a British Cabinet minister responsible for dealing with the United Kingdom's relations with members of the Commonwealth of Nations (its former colonies). The minister's department was the Commonwealth Office.

The position was created on 1 August 1966 by the merger of the old positions of Secretary of State for Commonwealth Relations and Secretary of State for the Colonies. In 1968 the position was merged with that of Secretary of State for Foreign Affairs to create the new position of Secretary of State for Foreign and Commonwealth Affairs.

Secretaries of State for Commonwealth Affairs, 1966–1968

	Term of office		Political party		F.Sec.
Herbert Bowden	1 August 1966	29 August 1967	Labour	Wilson	Stewart
Herbert Bowden	1 August 1966	29 August 1967	Labour		G.Brown
George Thomson	29 August 1967	17 October 1968	Labour		G.Brown
George Thomson	29 August 1967	17 October 1968	Labour		Stewart

History of English and British government departments with responsibility for foreign affairs and those with responsibility for the colonies, dominions and the Commonwealth
Northern Department 1660–1782 Secretaries — Undersecretaries	Southern Department 1660–1768 Secretaries — Undersecretaries		—
	Southern Department 1768–1782 Secretaries — Undersecretaries 1782: diplomatic responsibilities transferred to new Foreign Office	Colonial Office 1768–1782 Secretaries — Undersecretaries
Foreign Office 1782–1968 Secretaries — Ministers — Undersecretaries	Home Office 1782–1794 Secretaries — Undersecretaries
	War Office 1794–1801 Secretaries — Undersecretaries
	War and Colonial Office 1801–1854 Secretaries — Undersecretaries
	Colonial Office 1854–1925 Secretaries — Undersecretaries		India Office 1858–1937 Secretaries — Undersecretaries
	Colonial Office 1925–1966 Secretaries — Ministers — Undersecretaries	Dominions Office 1925–1947 Secretaries — Undersecretaries
			India Office and Burma Office 1937–1947 Secretaries — Undersecretaries
		Commonwealth Relations Office 1947–1966 Secretaries — Ministers — Undersecretaries
	Commonwealth Office 1966–1968 Secretaries — Ministers — Undersecretaries
Foreign and Commonwealth Office 1968–2020 Secretaries — Ministers — Undersecretaries
Foreign, Commonwealth and Development Office Since 2020 Secretaries — Ministers — Undersecretaries