The Philippine Institute of Environmental Planners (PIEP) was then formally established on October 16, 1969 with the approval of its charter by the Securities and Exchange Commission.

The Philippine Institute of Environmental Planners (PIEP) was an offshoot of R.A. 4341 which was signed into law on June 18, 1965 and provided for the establishment of the Philippine Institute of Environmental Planning as an academic unit of the University of the Philippines. After noting the increasing number of graduates produced by the Institute, the PIEP was organized as a national association of professionally trained planners who will advance the study of environmental planning in the best interest of the nation as well as promote the professional status of environmental planners.

A joint resolution in June 1968 by the Congress of the Philippines was adopted declaring the national policy of comprehensive environmental planning to implement the conservation, rehabilitation and development of human settlement and the natural environment through comprehensive integrated planning and management.