The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on the Human Environment in Stockholm in June 1972. Its mandate is to provide leadership, deliver science and develop solutions on a wide range of issues, including climate change, the management of marine and terrestrial ecosystems, and green economic development. The organization also develops international environmental agreements; publishes and promotes environmental science and helps national governments achieve environmental targets.

As a member of the United Nations Development Group, UNEP aims to help the world meet the 17 Sustainable Development Goals.

UNEP hosts the secretariats of several multilateral environmental agreements and research bodies, including The Convention on Biological Diversity (CBD), The Minamata Convention on Mercury, The Basel, Rotterdam and Stockholm Conventions, The Convention on Migratory Species and The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), among others.

In 1988, the World Meteorological Organization and UNEP established the Intergovernmental Panel on Climate Change (IPCC). UNEP is also one of several Implementing Agencies for the Global Environment Facility (GEF) and the Multilateral Fund for the Implementation of the Montreal Protocol.

UNEP sometimes uses the alternative name UN Environment.

Its headquarters is in Nairobi, Kenya.