The name, Casiguran, is conjectured to derive from Gugurang,[5] after the deity of the indigenous Ibalon peoples of Southern Luzon, from the provinces vulnerable to the turbulences of Mayon Volcano.

Gugurang, the "god of Good" who dwells inside of Mount Mayon is the guardian and protector of the sacred fire — which Asuang, his brother, tries to steal.

When displeased, Gugurang would cause Mayon Volcano to erupt,[8] but the lava also made the surrounding lands fertile.

Prior to their arrival, early settlers were the Dumagats, Aetas, and Bugkalots followed by migrants from other parts of the Philippines.

[11][12] In 1818, Nueva Ecija annexed the towns of Casiguran, as well as Baler, Infanta (formerly called Binangonan de Lampon) and Polillo Islands from Tayabas, and Palanan from Isabela.

[further explanation needed] When the Philippines regained sovereignty in 1946, Aurora was still part of Tayabas and Casiguran was a lone northern town.

In 1959 and 1966, the barrios of Dilasag and Dinalungan, which were part of Casiguran and situated on its northern and south-western portions, were made into municipalities.

It is bounded on the north-east by Dilasag, south-west by Dinalungan, north-west by Quirino and southeast by the Philippine Sea.