Raúl Prebisch was the Secretary-General (1963–1969).

In response to developing country (Least Developed Country, LDC) anxiety at their worsening position in world trade, the United Nations General Assembly voted for a 'one off' conference. These early discussions paved the way for new IMF facilities to provide finance for shortfalls in commodity earnings and for the Generalised Preference Schemes which increased access to Northern markets for manufactured imports from the South. At Geneva, the LDCs were successful in their proposal for the conference with its secretariat to become a permanent organ of the UN, with meetings every four years. At the Geneva meeting, Raul Prebisch—a prominent Argentinian economist from the United Nations Economic Commission on Latin America and the Caribbean (ECLA)--became the organization's first secretary-general.

The New Delhi Conference, held in February and March 1968, was a forum that allowed developing countries to reach an agreement on the basic principles of their development policies. The conference in New Delhi was an opportunity for schemes to be finally approved. The conference provided a major impetus in persuading the North to follow up UNCTAD I resolutions, in establishing generalized preferences. The target for private and official flows to LDCs was raised to 1% of the North's GNP, but the developed countries failed to commit themselves to achieve the target by a specific date. This has proven a continuing point of debate at UNCTAD conferences. The conference led to the International Sugar Agreement, which seeks to stabilize world sugar prices.

Manuel Pérez-Guerrero was appointed Secretaries-General from 1969 to 1974.

The Santiago Conference, 15 April 1972, was the third occasion on which the developing countries have confronted the rich with the need to use trade and aid measures more effectively to improve living standards in the developing world. Discussion centered on the international monetary system and specifically on the South's proposal that a higher proportion of new special drawing rights (SDRs) should be allocated to LDCs as a form of aid (the so-called 'link'). In Santiago, substantial disagreements arose within the Group of 77 (G77) despite pre-conference meetings. There was disagreement over the SDR proposal and between those in the G77 who wanted fundamental changes such as a change in the voting allocations in the South's favor at the IMF and those (mainly the Latin American countries) who wanted much milder reforms.

Gamani Corea was the Secretary-General of the United Nations Conference on Trade and Development and Under-Secretary-General of the United Nations from 1974 to 1984.

UNCTAD IV held in Nairobi in May 1976, showed relative success compared to its predecessors. An Overseas Development Institute briefing paper of April 1979 highlights one reason for success as being down to the 1973 Oil Crisis and the encouragement of LDCs to make gains through producers of other commodities. The principal result of the conference was the adoption of the Integrated Programme for Commodities. The programme covered the principal commodity exports and its objectives aside from the stabilization of commodity prices were: 'Just and remunerative pricing, taking into account world inflation', the expansion of processing, distribution, and control of technology by LDCs, and improved access to markets.

UNCTAD V in the wake of the Nairobi Conference, held in Manila 1979 focused on the key issues of protectionism in developing countries and the need for structural change, trade-in commodities and manufactures aid and international monetary reform, technology, shipping, and economic cooperation among developing countries. An Overseas Development Institute briefing paper written in 1979 focuses its attention on the key issues regarding the LDCs` role as the Group of 77 in the international community.

The sixth UN conference on trade and development in Belgrade, 6–30 June 1983 was held against the background of earlier UNCTADs which have substantially failed to resolve many of the disagreements between the developed and developing countries and of a world economy in its worst recession since the early 1930s. The key issues of the time were finance and adjustment, commodity price stabilization, and trade.

Alister McIntyre was the Officer-in-Charge in 1985.

Kenneth K.S. Dadzie was appointed to lead United Nations Conference on Trade and Development from 1986 to 31 March 1994.

The Seventh conference was held in Geneva, Switzerland from 8 July to 3 August 1987.

UNCTAD Eighth Conference was held in Cartagena, Colombia.

Carlos Fortin was Officer-in-Charge from 1994 to 1995.

Rubens Ricupero served as the fifth Secretary-General of the United Nations Conference on Trade and Development from September 1995 to September 2004.

Ninth Conference "UNCTAD IX" was held in Midrand, South Africa, from 27 April to 11 May 1996.

"UNCTAD X" was held in Bangkok, Thailand.

"UNCTAD XI" was held in São Paulo, Brazil, from 13 to 18 June 2004.

Carlos Fortin was the Officer-in-Charge from 2004 to 2005.

Supachai Panitchpakdi was Secretary-General of the UN Conference on Trade and Development (UNCTAD) from 1 September 2005 to 31 August 2013.

UNCTAD XII was held in Accra, Ghana, from 21 to 25 April 2008.

UNCTAD XIII was held in Doha, Qatar, from 21 to 26 April 2012.

Mukhisa Kituyi served as Secretary-General of the United Nations Conference on Trade and Development, UNCTAD from September 2013-February 2021.

UNCTAD XIV was held in Nairobi, Kenya, from 17 to 22 July 2016.

On 16 February 2021, Durant replaced Mukhisa Kituyi at the head of the organization, becoming acting Secretary-General until June 2021.

Rebeca Grynspan Mayufis has been serving as Secretary-General of the United Nations Conference on Trade and Development (UNCTAD) since 13 September 2021.

UNCTAD XV was held in Bridgetown, Barbados, from 3 to 8 October 2021.