Headquarters in London, the IMO is a specialized agency of the United Nations established in 1948, with 168 member nations and three associate members. The IMO deals with various aspects of the regulation of international commercial shipping, encouraging cooperation among governments in a wide variety of technical matters. Additionally, the agency supports high standards in maritime safety, promotes efficient navigation, and encourages the control and prevention of marine pollution. It has the power to enforce and administer matters relating to these objectives. In the early 21st century, the IMO has placed an increased emphasis on maritime security.

As one of the smallest of the UN agencies, IMO was renamed from the original Inter-Governmental Maritime Consultative Organization.