The position of Under-Secretary of State for Dominion Affairs was a British ministerial position, subordinate to that of Secretary of State for Dominion Affairs, created in 1925 to deal with British relations with the Dominions – Canada, Australia, New Zealand, South Africa, Newfoundland, and the Irish Free State.

In 1947 the office was replaced by the Under-Secretary of State for Commonwealth Relations.

Under-Secretaries of State for Dominion Affairs, 1925-47

Permanent Under-Secretaries of State for Dominion Affairs, 1925-47

The post lasted as long as the office itself, from 1925 to 1947 with the last Permanent Under-Secretary of State for Dominion Affairs, Sir Eric Machtig, transferring in 1947 to become the Permanent Under-Secretary of State for Commonwealth Relations, jointly with A. Carter formerly of the India Office.

Name	Entered office	Left office
Sir Charles Davis	1925	1930
Sir Edward Harding	1930	1939
Sir Eric Machtig (acting)	1939	1940
Sir Cosmo Parkinson	1940	1940
Sir Eric Machtig	1940	1947

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