UN-Oceans is an inter-agency mechanism that seeks to enhance the coordination, coherence and effectiveness of competent organizations of the United Nations system and the International Seabed Authority, within existing resources, in conformity with the United Nations Convention on the Law of the Sea, the respective competences of each of its participating organizations and the mandates and priorities approved by their respective governing bodies.

UN-Oceans is to: (a) Strengthen and promote coordination and coherence of United Nations system activities related to ocean and coastal areas; (b) Regularly share ongoing and planned activities of participating organizations within the framework of relevant United Nations and other mandates with a view to identifying possible areas for collaboration and synergy; (c) Facilitate, as appropriate, inputs by its participating organizations to the annual reports of the Secretary-General on oceans and the law of the sea and on sustainable fisheries to be submitted to the Secretariat; (d) Facilitate inter-agency information exchange, including sharing of experiences, best practices, tools and methodologies and lessons learned in ocean-related matters.

Following the Earth Summit in Rio de Janeiro on June 13, 1992, 178 United Nations member states came to a consensus on Agenda 21, an action plan designed to promote sustainable living in the 21st century.

Instead, they recommended that task-oriented arrangements, especially those concerning the world's oceans, and any inter-agency support requirements should be overseen by a designated lead agency.

On October 31, 2003, the United Nations System Chief Executives Board for Coordination (CEB) endorsed the decision made by the High-Level Committee on Programs (HLCP) to establish a network focused on ocean and coastal areas, originally named OCAN and later rebranded as UN-Oceans.