The deputy secretary-general of the United Nations is the deputy to the secretary-general of the United Nations. The office was created to handle many of the administrative responsibilities of the secretary-general, help manage Secretariat operations, and ensure coherence of activities and programs.^[2][3] The post was formally established by the General Assembly at the end of 1997.^[1]

Amina J. Mohammed of Nigeria was named as deputy secretary-general by then secretary-general-designate António Guterres. Mohammed assumed the office the same day as Guterres began his term, on 1 January 2017.

Responsibilities generally delegated by the secretary-general to the deputy secretary-general include:^[4]

(a) To assist the Secretary-General in managing the operations of the Secretariat;

(b) To act for the Secretary-General at United Nations Headquarters in the absence of the Secretary-General and in other cases as may be decided by the Secretary-General;

(c) To support the Secretary-General in ensuring inter-sectoral and inter-institutional coherence of activities and programs and to support the Secretary-General in elevating the profile and leadership of the United Nations in the economic and social spheres, including further efforts to strengthen the United Nations as a leading centre for development policy and development assistance;

(d) To represent the Secretary-General at conferences, official functions and ceremonial and other occasions as may be decided by the Secretary-General;

(e) To undertake such assignments as may be determined by the Secretary-General;

The director in the Office of the Deputy Secretary-General is a sitting observer of the United Nations Development Group.^[5]

Canadian Louise Fréchette was the first deputy secretary-general of the United Nations, holding the position from 1998 to 2005. She was appointed to the post by Secretary-General Kofi Annan and assumed her duties on 2 March 1998. In 2005, partly in response to criticism by former U.S. Federal Reserve Chairman Paul Volcker for failed management of the Iraq Oil-for-Food Programme, Frechette announced her resignation. She remained at her post until 31 March 2006.^[4]

On 3 March 2006 it was announced that Mark Malloch Brown from the United Kingdom would succeed Louise Fréchette as deputy secretary-general on 1 April 2006. Brown left his post concurrent with Kofi Annan's departure as secretary-general on 31 December 2006.^[4]