GLAN SCHOOL OF ARTS AND TRADES (GSAT) is formerly known as Glan Vocational High School (GVHS) – a public vocational secondary school created by Republic Act No. 5379 in 1968 through the authorship of Congressman James L. Chiongbian then representing the lone district of South Cotabato. It became operational in 1971 with enrolment of 152 first year high school students. In school year 1975- 1976, GVHS opened the 2-year Trade Technical Program with an enrolment of 136 majoring in Technical Electricity, Technical Automotive, Technical Food Trades, Technical Garment Trades and Technical Machine Shop. To follow up the graduates of the two-year trade technical education program, in school year 1977- 1978 the school started the third year of the four-year industrial teacher education curriculum. The initial students of the diploma program were the 40 graduates of the trade technical education program. Its technical pioneering school administrator was Mr. Lorenzo Hablan Dideles (1971- 1977), followed by Mr. Nelson Herrera Dideles (1977- 1980), who retired early because of physical disability and was succeeded by Mr. Juanito Daquigan Abugan (1980-1989) who retired due to his force retirement. Mr. Antonio D. Jomillo Jr. took his leadership in 1989 and retired in 2010. In March 16, 2010 upon retirement of the latter, Mr. Renato Empleo Tamine was appointed as the Vocational School Administrator II who retired last November 25, 2015. By then The Vocational School Administrator II was vacated and remained vacant for almost 3 years. In order not to hamper its institutional operation, the school was under the stewardship of an Office In-Charge Ms. Glenda Lara-Elem-Principal I in 2015 until May 30, 2018. It was in June 1 , 2018 that the new Vocational School Administrator II Josie Teofila Nesle-Quijano was appointed and currently managing the school.

In 1979, the school administration requested Assemblyman Jose T. Sison to sponsor a bill changing the name of Glan Vocational High School. The effort of Assemblyman Sison brought about the passage of Batas Pambansa Bilang 781 which changed the name of the school into Glan School of Arts and Trades. The new law, however, did not change status of the school into higher education institution. Thus, it remained as a technical-vocational school. Nevertheless, there were many attempts by the school administration to elevate the status of the school into college. The former administrator – the late Lorenzo H. Dideles – during the Martial Law years worked for a presidential decree converting the school into Southern Philippines Institute of Technology. The University of Southern Mindanao then the Mindanao Institute of Technology also sent feelers to place the school under its wings when it was working out for the conversion of the college into a university. Assemblyman Bicbic Garcia in the late 1970’s also proposed for the clustering of General Santos National School of Arts and Trades, Glan school of Arts and Trades and Bula School of Fishery into a single state college

Through the resolutions made by the GSAT-PTA, the student body, and the Sangguniang Bayan of Glan, Congressman James L. Chiongbian introduced a bill in the House of Representatives in 1993 for the conversion of Glan School of Arts and Trades into a full-fledged college to be known as Glan Institute of Science and Technology. The bill reached the third reading in the lower house but its passage did not prosper because of the moratorium in the creation of state colleges and universities. In 1996 the bill was filed anew in the House of Representatives. Again it was not favorably acted upon until the end of the term Congressman James L. Chiongbian. A new bill for the conversion of the school into a state college (Sarangani Polytechnic State College) authored by Congressman Erwin L. Chiongbian who deliberated in the House of Congress and introduced in 2002.  

When RA No. 7722, otherwise known as the Commission on Higher Education, was implemented in 1996, the CHED wanted to get GSAT into its fold because of the collegiate (teacher education) program and being the only CHED-supervised institution in Region XI. However, the following year of the Technical Education and Skills Development Authority (TESDA) was quicker to the draw. TESDA was created by RA No. 7796 of 1995 is mandated to handle the technical- vocational non-degree programs in the country. It assumed the roles of the National Manpower Youth Counsel and the Bureau of Technical-Vocational Education. GSAT was put under the governance of TESDA for one school year (1991- 1998).

Another re-organization took place in 1998. The Glan School of Arts and Trades was re-classified and returned to DECS (now, DepEd) because of the predominant high school enrollment.

GSAT was defuncted to offer degree programs and also the post-secondary education programs. Thus, in school year 2000- 2001, GSAT turned out the concluding batches of industrial teacher education and the trade-technical education graduates. It was directed by DepEd to phase out the programs and has to concentrate on the improved delivery of high school education. GSAT is placed under the supervision of DepEd Sarangani Division.

From a mere 152 students way back in 1971, today the student population is 3471. The total number of high school graduates turned out by the school as of 2022 is 10,247 discounting its graduates of the two-year trade technical programs and the four-year industrial teacher education programs.

GSAT has 115 teaching staff and 30 administrative staff and support personnel.