In the year 2008, Mr. Licerio T. Napao was assigned as OIC-Schools Division Superintendent in the Division of Negros Oriental. Being the Head of the Department of Education in the Province he expanded the system by opening additional barangay high schools in different municipalities.

In his hometown he opened four high schools at the start of classes on June 2008 namely: Sumaliring High School, Cambonbon High School, Mantiquil Masaligan High School and Napacao High School with the coordination of the Municipal Mayor Vincent Emil T. Arbolado.

After few days of classes Mayor Vincent Emil T. Arbolado realized and decided to open a barangay high school in his own homeplace which is Giligaon as permitted by the Schools Division Superintendent. So, with the collaraborative efforts of the Barangay Officials headed by Capt. Dioscoro C. Gomez Jr. and the Sangguniang Bayan Members headed by the Municipal Vice-Mayor Hon. Roel Gabo, they passed a resolution to open a High School at Giligaon, Siaton, Negros Oriental.

On June 19, 2008 the opening of the new high school was realized and started the classes at the Giligaon Barangay Hall with two teachers namely: Ms. Rubilyn O. Sixto and Mrs. Elenita R. Macapangal who is designated as Teacher In-Charge.

The proposed school site was the Arbolado’s lot found at Looc, Giligaon but due to some constraints it was not push through and so the principal of Giligaon Elementary School Mr. Arturo Lajato with his teaching staff decided to slash and offer a portion of their school’s vacant land area for the high school. The total land area shared is 2,360 square meters using the legal document, Contract of USUFRUCT.

On the first week of September 2008 one unit 2-classroom school building started to rise and on the third week another 2 units 2-classroom school buildings rose up. It was on February 2009 the classes were transferred to the newly built school buildings and finally the school is here. Additional classrooms were added amidst the increasing number of enrollees. When K-12 was implemented on June 2016, an additional one (1) 2-story Senior High School building and a TVL laboratory was added.

Today, Giligaon High School is catering more than 500 high school students (junior and senior high school) headed by Regina A. Veran as Teacher In-Charge.