The United Nations Office for the Coordination of Humanitarian Affairs (OCHA) is a United Nations (UN) entity that was formed by the General Assembly in December 1991 to boost the global reaction to complex crises and natural calamities. It is the Office of the United Nations Disaster Relief Coordinator's successor.

The Secretary-General formed the Department of Humanitarian Affairs (DHA) shortly after, but it was incorporated into OCHA in 1998, which became the UN's main focal point for severe catastrophes. OCHA's role was later expanded to encompass humanitarian response coordination, policy analysis, and humanitarian advocacy. Its operations include coordinating and monitoring humanitarian funds, lobbying, policy development, and information exchange to assist rapid-response teams for disaster aid.

The Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator (USG/ERC), who is appointed for a five-year term, leads OCHA.The 2016 World Humanitarian Summit was organized by OCHA in Istanbul, Turkey.