UNOPS origins trace back to 1973, and until 1994 the Office for Project Services was part of UNDP. By decision of the General Assembly, UNOPS became a separate, self-financing entity within the UN development system on 1 January 1995.

On 20 December 2010, the United Nations General Assembly adopted a resolution in which the 192 member states reaffirmed UNOPS mandate and the range of partners that the organisation can work with. ​

The re
solution also endorsed a number of earlier decisions taken by the Economic and Social Council of the Gen​​​eral Assembly and UNOPS Executive Board regarding the organization.

The Assembly highlighted UNOPS role as a central resource for the United Nations system in procurement and contract management as well as in civil works and physical infrastructure development, including the related capacity development activities.

The resolution also recognized the potential for value-adding contributions that UNOPS can make in providing efficient, cost-effective services to partners in the areas of project management, human resources, financial management and common/shared services.

In the context of coherence and the furthering of United Nations objectives, UNOPS may act as a service provider to various actors in the development, humanitarian and peacekeeping arenas, including the United Nations, its agencies, funds and programmes, donor and recipient governments, intergovernmental organizations, international and regional financial institutions, non-governmental organizations, foundations and the private sector.

The Assembly also decided to rename the Executive Board to include UNOPS in its title, making it the Executive Board of the United Nations Development Programme, the United Nations Population Fund and the United Nations Office for Project Services. It furthermore endorsed an earlier decision concerning the governance structure of UNOPS whereby the Executive Director reports directly to the UN Secretary-General and the Executive Board, and has the authority to sign host country agreements and appoint UNOPS representatives in the field.

The full text of the above legislative documents can be found in General Assembly resolution A/RES/65/176,  adopted at its 65th session in December 2010, the ECOSOC resolution 2010/23 (July 2010) and the Executive Board decisions 2008/35 (September 2008), 2009/25 (September 2009), 2010/7 ( January 2010) and 2010/21 (June 2010).