The First source of funding for UNEP was provided for in the UN General Assembly resolution 2997 (XXV11) in 1972.

When the United Nations Environment Programme, was established the Assembly decided "That the costs of servicing the Governing Council and providing the small secretariat shall be borne by the regular budget of the United Nations..."

The regular budget provides core support to UNEP, and is utilized for policy-making, executive direction and management, development of programme of work and programme support. In 1973, UNEP received $1.75 million from the regular budget, i.e. 21.1% of its total financial resources that year. The corresponding figures for 1981 were US$5.3 million or 12.8%, for 1991 US$6.16 million or 6.8% and in 2002 US$4.5 million or 3.6%.

In 2006-2007, US$ 13.385 million was directly allocated to UNEP and administered by the headquarters, with part of the funds allocated to UNEP offices in New York and Geneva and to the United Nations Scientific Committee on the Effects of Atomic Radiation(UNSCEAR) in Vienna. The Regular budget contribution was equal to approximately 5.1% of the total annual income to the budget of UNEP, excluding contribution from GEF.

In 2008-2009 the appropriations from the Regular budget is at the slightly lower level of US$12.93 million. This is equal to approximately 3.1% of the total expected income in 2008, excluding contribution from GEF.

Furthermore, UNEP receives grants from the UN Development Account, which is part of the Regular budget. These funds are used to support selected UNEP project activities on issues of development and environment. In 2006-2007 UNEP received US$2.2 million and in 2008-2009 the financial support will reach US$2 million.