The Defence Council was formed in 1922 under the National Defence Act which created a single Department of National Defence. Its role evolved over time with changes in the administration of defence. During the Second World War, the Council co-ordinated matters between the three separate departments for the Navy, Army and Air Force. Each Department had a separate Minister and Deputy Minister and the Minister for the Army was appointed as the Minister for National Defence. The Defence Council consisted of the Minister for National Defence who served as Chairman, the other two Ministers, the three Chiefs of Staff and the three Deputy Ministers who served as members with the Defence Secretary serving as Secretary.

On 12 December 1946, the three separate departments were again integrated into a single Department of National Defence under the Honourable Brooke Claxton. The role of co-ordination between the forces diminished in importance. The Defence Council was formally reconstituted by PC 887 on 13 March 1947 with the Minister of National Defence serving as Chairman. The Parliamentary Assistant, the Deputy Minister, the Associated Deputy Ministers, the three Chiefs of Staff and the Chairman of the Defence Research Board served as members. Other Officers attended as required with the Defence Secretary continuing in the role of secretary. The Council was now a preliminary forum to advise the Minister on administrative matters.

In 1950, under the new National Defence Act, the Minister or Associate Minister of National Defence served as Chairman with the Parliamentary Secretary, Deputy Minister of National Defence, Associate Deputy Minister of National Defence, Chairman, Chiefs of Staff and the Chairman of the Research Board serving as members. The Council continued to advise the Minister on non-operational policy. Two committees, the Personnel Members Committee and the Principal Supply Officers Committee, reported to Defence Council. Various sub-committees and working groups reported to these two committees on matters of administrative interest.

With the abolishment of the Chiefs of Staff Committee in July 1964 under the Honourable Paul Hellyer, the Defence Council became the primary forum for the formulation of departmental policy. It was re-organized yet again with the Minister as Chairman, the Associate Minister as Vice-Chairman, and the Chief and Vice-Chief of the Defence Staff, the Chairman of the Defence Research Board and the Deputy Minister as members. Branch Heads and relevant Assistant Deputy Ministers, other government department representatives attended as required. A senior officer of External Affairs attended regularly. The Defence Council met more often and played an important role during the period of rapid change from 1964 to 1971. In 1971, with the introduction of the Defence Management Committee under the Honourable Donald MacDonald, the Defence Council ceased to be as significant in policy development as its role was usurped to some degree by this Committee.