Extension as an institutional function started sometime in 1974 under the stewardship of Jose Lacson under the name, Extramural Studies and extension Services (ESES). Its main program component was Rural Life Development, hence the Institute of Rural Life Development (later renamed as Institute of Rural Life Technology (IRLT) which offered a four-year secondary agri-based program in 1975. Graduates of the program were encouraged to enter into two-year vocational course which was also agri-based, a response to the government thrust of promoting agricultural development in the countryside under the directory of Prof. Rizal V. Ganiban.
Then in 1983, it the ESES was reestablished as a separate office directly under the office of the College President with Professor Adoracion Y. Nogoy. It offered non-formal education program which aimed to help the out-of-school youth, continuing education and special projects in enhancing the effectiveness of other sectors. The office was also tasked to monitor income generating projects of the college. Believing that the extension is not only for the outside clients, projects like success lessons and evaluation for the faculty and staff were also initiated and taken care of by the office.
When Dr. Ernesto Cosme was appointed as the OIC President of Tarlac State University in 1992, the extension and research were merged into one under the dictatorship of Prof. Nogoy. When Dr. Alejandro Fernandez was appointed as the president of the university and the retirement of Dr. Nogoy happened, the dictatorship was turned over to Dr. Alfredo M. Conte. In 1995, Dr. Rodolfo Baking took over the presidency of the university, he separated the research from extension. The research was under the dictatorship of Dr. Victoria Gengania, while Dr. Conte continued his stewardship as the Director of Extension. This led to the designation of chairmen to take charge of the various functions and areas of concern and programs and also the designation of College Extension Coordinators whose main function is to serve as link between the University Extension Office to the various colleges. Extension Initiative were undertaken collaboration with civic organizations, religious organizations and local government units. The granting of level of III A status of the university under the leadership of President Dolores G. Matias, Dr. Gengania was appointed as Vice President for Planning, Research and Extension in 2002. She filed her one-year Sabbatical leave starting June 2005 and Dr. Conte took over her position as OIC up to his retirement on March 6, 2006.
Upon his retirement, Dr. Glenard Madriaga took over the dictatorship who is committed to extend quality services by sharing the university's expertise in uplifting the socio-cultural, technological, educational and environmental condition of the populace towards sustainable development. Under his leadership, the University Extension Manual was approved by the Board of Regents under Resolution No. 39 series of 2008 dated June 9, 2008.
His appointment as the Vice President for Research, Extension and Development on February 16, 2008 led to designation of Prof. Redemptor G. Toledano, serving then as Cluster Chairman for Consultancy and Special Project, as the Director of UEO up to the present. The office was able to develop strategies and expanded the operations and services, particularly in line with the Community Development Modeling Program which provides assistance in identifying the needs of a community and matching these with the capabilities of the institution; the Industry Development Extension Program which is aimed at providing services to small and medium enterprises in order to increase their productivity; the Institution-Public-Private Sector Partnership program; the Extension Support Services Program and the Student Extension Experience Program. It was during the leadership of the latter that an effort to align the operation of the unit to ISO 9001:2008 was undertaken with the end-view of eventually being certified accordingly. Hence, the University Extension Manual was converted into the TSU Extension Services Guide under BOR Resolution No. 66 series of 2009 dated November 4, 2009.
Through effort and commitment, in 2016, the office established another program namely, Professional Development Program to assist professional in enhancing the level of professionalism and integrity of their members by conducting trainings and consulting activities to requesting parties free of charge through Continuing Education and offered trainings and seminars for a fee where CSC accredited and speakers were invited outside or tapped among the faculty pool of experts, providing them with lifelong learning. On September 2017, the board approved the establishment of Regional Center for Resource Development of Indigenous Peoples (RCRDIP) including the required budget and the manpower complement for the operation to provide technical support for the protection and promotion of the interest and well-being of indigenous people (IPs) that covers the provision of trainings, seminars, technical assistances, consultancy services ¬and conduct of coaching and mentoring activities. This is also in pursuance with the Republic Act No. 8371 otherwise known as Indigenous Peoples Rights Act of 1997 which aims to recognize and promote all the rights of Indigenous Cultural Communities/Indigenous Peoples (ICCs/IPs).