The Duke of Wellington spearheaded the establishment of RUSI in a letter to Colbourn's United Service Journal arguing that "a United Service Museum" should be formed, managed entirely by naval and military officers, and under patronage of the monarch, then King George IV, and the commanders-in-chief of the armed forces.

Such an institution would prove that the two professions have entered the lists of science, and are ready to contend for honours tam Artibus quam Armis ('as much through the arts as through weapons').

[2] Subsequently, Commander Henry Downes, Royal Navy, assembled a group with a view to forming a committee for action, to which King George's First ADC was commanded to convey "His Majesty's gracious and high approbation of the undertaking and of the principles on which it is proposed to conduct it", which were stated to be suitable for "a strictly scientific and professional society, and not a club".

The chair was taken by Major General Sir Howard Douglas, in his person a symbol of the "United Service": a soldier who was the leading expert on naval gunnery.

[8] RUSI has a membership consisting of military officers, diplomats and the wider policy community, numbering 1,668 individuals and 129 corporate members (see the last page of the latest Review).

[9] OpenDemocracy criticized RUSI being presented as apolitical by news outlets such as the BBC, considering the organization has "close links with the British state and its military establishment," but also recognized its analysts to be "highly informed and often insightful.

[12] RUSI experts are often called upon to provide analysis and commentary on the leading defence and security issues of the day.

[20][21] Major contributors include the U.S. Department of State, the UK Foreign, Commonwealth & Development Office, the European Commission and BAE Systems.