The Balfour Declaration of 1926 is a statement of the October-November 1926 Imperial Conference of British Empire leaders in London. It states that the United Kingdom and the Dominions "are autonomous Communities within the British Empire, equal in status, in no way subordinate one to another in any aspect of their domestic or external affairs, though united by a common allegiance to the Crown, and freely associated as members of the British Commonwealth of Nations".

The statement should not be confused with the Balfour Declaration of 1917 by which the British foreign minister favoured a Jewish national home in Palestine. It is named, like the earlier document, after the Earl of Balfour (Arthur James Balfour, 1848-1930), Lord President of the Council in the British government and chairman of the Conference's inter-Imperial relations committee. The committee drew up the document preparatory to its approval by the Imperial premiers at their sitting of November 15.

The Declaration formally accepted the growing political and diplomatic independence shown particularly by Canada since World War I. It also accepted that the Governor-General, the representative of the King, who remained head of state in each Dominion, should no longer serve automatically also as the representative of the British government in diplomatic relations between the two countries. This foreshadowed the appointment (1928) of a British High Commissioner in Ottawa.

The conclusions of the Conference were re-stated by that of 1930 and incorporated in the December 1931 Statute of Westminster by which Parliament renounced any legislative authority over Dominion affairs except as specifically provided in Dominion law.