Michael Zammit Cutajar devoted most of his career to work in and around the United Nations on international cooperation for development and environment. In 1991, he set up the secretariat of the United Nations Framework Convention on Climate Change (UNFCCC) and headed it as Executive Secretary until his retirement early in 2002, holding the rank of Assistant Secretary-General of the United Nations.

Between 2002 and 2011, Mr. Zammit Cutajar advised the Government of Malta pro bono on climate change and international environmental issues. In the capacity of Malta's Ambassador on Climate Change, he participated in the work of the European Union and the UNFCCC. In the latter framework, he served as Chair of the Ad Hoc Working Group on the Kyoto Protocol (2006) and as Vice-Chair and Chair of the Ad Hoc Working Group on Long-term Cooperative Action (2008-2009) – the two negotiating tracks towards agreement on stronger international action to address climate change.

In that period, he also served on bodies providing advice to the World Bank and the European Commission, among others.

In the 2007 Republic Day honours list, Mr. Zammit Cutajar was appointed Member of the National Order of Merit of Malta. In 2009, he was awarded the Knight's Cross in Hungary's Order of Merit (Civil Division)  and, in 2012, he was made Chevalier of France’s Légion d’Honneur.

Mr. Zammit Cutajar – a citizen of Malta, born 1940 - was educated at St. Edward's College, Malta, and the University of London. His work outside the United Nations framework included assignments with the Uganda Development Corporation, Kampala (1963-65), the Overseas Development Institute, London, UK (1965-67) and International Foundation for Development Alternatives, Nyon, Switzerland (1978-81). The first part of his United Nations career included postings with the UN Conference on Trade and Development (1967-71, 1974-78, 1986-91) the UN Conference on the Human Environment (1971-72) and the UN Environment Programme (1972-74).