Achim Steiner was appointed Senior Fellow of the Oxford Martin School on 12 January 2026.  Prior to joining the University of Oxford he served as United Nations Under-Secretary General and Administrator of the United Nations Development Programme (2017 -2025).

During his tenure at the United Nations, Mr Steiner led UNDP - the largest of the UN development agencies with a presence in over 170 countries and territories - through significant programmatic innovation and established UNDP as a central global player on issues such as climate change, technology innovation, ecosystems management and the role of finance, markets and the private sector in sustainable development and innovation. During his 8 year tenure he also served as Vice-Chair of the UN Sustainable Development Group and as Managing Director of the UN Capital Development Fund. 

In 2016 Mr. Steiner was appointed Director of the Oxford Martin School/University of Oxford and Professorial Fellow of Balliol College.

From 2006-2016 he served as Executive Director of the UN Environment Programme (2006 - 2026) and also led UNEP through a major reform and transformation process culminating in the UN General Assembly establishing a new UN Environment Assembly in 2014, to foster more effective global environmental cooperation and governance. During his tenure in Nairobi, he pioneered a number of new major initiatives linking economic and environmental transitions such as on the green economy, finance, energy, and natural resources management. Mr Steiner also served as a member of the UN Secretary General’s Chief Executive Board and chaired the UN System’s High Level Committee on Programmes.

During his career, which he began as a development economist and which gradually led him into the broader arena of sustainable development, international relations and global diplomacy, Mr Steiner has led a number of institutions as Chief Executive, including as Secretary General of the World Commission on Dams, Director General of the International Union for the Conservation of Nature (IUCN), Director General of the United Nations Office at Nairobi (UNON) . He has lived and worked in Oman, UK, India, Pakistan, Germany, Zimbabwe, USA, Vietnam, South Africa, Switzerland and Kenya.

He currently serves on a number of Boards and Councils – including as Chair of the Hamburg Sustainability Conference (HSC), as International Vice-Chair of the China Council for International Cooperation on Environment and Development (CCICED), Chair of the AGORA Verkehrswende (Mobility Transition) Council, member of the the Board of the Climate Works Foundation and since February 2026 as member of the German Chancellor’s Council for Sustainable Development.

Mr Steiner was born in Brazil and holds both Brazilian and German nationality. He graduated in Philosophy, Politics and Economics (MA) at the University of Oxford, holds an MA from the School of Oriental and African Studies/University of London (SOAS), and completed his post-graduate studies at the German Development Institute as well as the Harvard Business School Executive Programme. He has been awarded a doctorate honoris causa by the International University in Geneva and is an Honorary Professor at Tongji University, Shanghai. His work and leadership have been recognised through numerous awards such as the Talberg Foundation's Award for Principled Pragmatism, the Bruno H. Schubert Prize for Environmental Leadership, the Slovak Republic's Gold Medal for Diplomatic Service, the Republic of Korea Order of Diplomatic Service Award and the German Sustainability Award. Mr Steiner was appointed an Officer of the Order of St Charles.