Born in Guyana, Miles Stoby was educated in the U.K., with a degree in Economics and Political Science from St.John's College, Cambridge, before joining the Guyanese foreign service. He quickly reached ambassadorial rank and was posted to the Guyanese Mission to the United Nations.

In 1978 he joined the U.N. Secretariat. Among his appointments, his role as Secretary organising the 1992 Rio Earth Summit on Environment and Sustainable Development reflected his previous wide-ranging involvement with both people and complex issues, establishing the United Nations global sustainable development goals.

In 2001, Secretary General Kofi Annan appointed Miles Stoby as Assistant S.G. For General Assembly Affairs and Conference Services. Other key career roles included the organisation of the Millennium Summit, coordinating the UN Reform and organising the U.N.'s Small Islands Conference.