The name Mahayag was derived from a native Subanen dialect which means “Boyed Mahayag”, a term that insinuates for fertile alps and mountainous expanse due to the profusion of pristine forest, hedging plants, vegetation, and animals living in a natural undomesticated state. Subanens, who lived along river banks, were the first settlers of Mahayag; they have refined the breadth of land and crafted it into an economic state of livelihood, enriching the primeval vegetation they envisioned of culturing for their succeeding generations. At this spot, they pitched camp and claim the land to hone it and further develop their own small civilization.

Christians inhabited the plains of Mahayag to seek for greener pastures and to pursue more productive land to cultivate sometime in the late 1930’s. Subanens then retreated to the uphill lands in search for plain land for farming. The opportunity for a new-fangled life was found at last, and subsequently it was of essence that such prospect be pursued to the end. Mahayag expanded into a prosperous community owing to the perseverance and persistence of purpose of the first settlers.

Consequently, Mahayag was formally imprinted out from the Municipalities of Molave and Dumingag on March 9, 1960 through the virtue of Executive Order No. 393 that was issued by the former President of the republic of the Philippines, his exellency Carlos P. Garcia. The new municipality was urbanized and merged to be one of the novel emergent communities in the entire province of Zamboanga del Sur.

At the present time, Mahayag is constitutionally subdivided into 29 Barangays. One of which is Barangay San Vicente.