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 Foreign Secretary.