The United Nations Office (UNO) at Vienna (UNOV) is one of the four major office sites of the United Nations where numerous different UN agencies have a joint presence. The office complex is located in Vienna, the capital of Austria, and is part of the Vienna International Centre, a cluster of several major international organizations. UNOV was established on 1 January 1980, and was the third such complex to be created.

The United Nations (UN) is a diplomatic and political international organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and serve as a centre for harmonizing the actions of nations. It is the world's largest international organization. The UN is headquartered in New York City, and the UN has other offices in Geneva, Nairobi, Vienna, and The Hague, where the International Court of Justice is headquartered at the Peace Palace.