The Department of Environmental Science (DOES) was formed in 2013 to centralize the offering of programs and courses in environmental science, management and studies as well as the earth sciences.  Prior to the creation of the department, the graduate programs in environmental management were being offered by the Institute of Climate Change and Environmental Management (ICCEM) while the undergraduate curriculum in environmental science was being administered by the Department of Biological Sciences.  The courses in the earth sciences were being handled by the Department of Chemistry.  These programs and courses were brought together under one unit as part of the effort of the university to implement the vertical articulation of graduate programs.  In 2018, the department began to administer the existing distance learning programs in environmental management in collaboration with the Distance, Open, and Transnational University (DOT-Uni).

Initially, the department was manned by three core faculty members. Today, it has eight core faculty members with advanced degrees in the various subfields or allied disciplines of environmental science.  Since 2013, personnel from the other departments of the then College of Arts and Sciences, as well as from the other colleges (Agriculture and Engineering) and research and development centers (ICCEM, Research Office, and the Ramon Magsaysay Center for Agricultural Research and Environment Studies [RMCARES], Center for Tropical Mushroom Research and Development [CTMRD]) in the university have been handling courses for the department or supervising student research. 

The department has received grants from national funding agencies for research projects on waste valorization and sustainable drug discovery as well as university grants to implement projects on biodiversity and solid waste management.  Its core faculty members have published research articles on environmental biotechnology, environmental parasitology, and green technology. In 2014, the department served as host to a Canadian professor who conducted training-workshops on green chemistry education that it co-organized.  A US Peace Corps Response Volunteer was also assigned to the department in 2019.  The volunteer worked with the department on its extension work on community-based environmental management.

The department produced its first BS in Environmental Science graduates in 2016 and its first PhD in Environmental Management graduate in 2016.  It welcomed its first international student in 2018, the same year when one of its BS Environmental Science student was chosen to represent CLSU on a BPI-DOST Science Awards.