Formerly a barrio of the Municipality of Cauayan, Candoni started as the center of the Tabla Valley Settlement founded in 1935 by Santiago H. Diego, a prominent man from the Municipality of Isabela. He led a group of settlers with a pioneering spirit and prompted by the desire to have a piece of land they could call their own. Pooling their resources and organizing themselves into a cooperative they called Tablenos, the settlers started clearing the valley starting from where the town is now located. They toiled the forests enduring hardships, but many of them died of malaria.

Their efforts were noticed by the Provincial Government who supported them, starting with Gov. Emilio Gaston to Gov. Valenciano Gatuslao, who along with then Speaker Gil Montilla, helped them appeal to President Manuel Roxas in Malacanang for tangible government aid, which came in the form of the road from Dancalan, Ilog to Candoni, following the trail blazed by the Tablenos. Candoni was finally declared a municipality on August 22, 1958 throuh Executive Order No. 314 signed by President Carlos P. Garcia. It was inaugurated on August 12, 1961, with Benjamin R. Nava as its first acting mayor. 

Recent history of Candoni again showed its people’s struggle, this time, against the turmoils brought about by the insurgency problem. Fed up with being caught in the crossfire of battles between rebels and government forces, the people of Sitio Cantomanyog in Brgy. Haba of the town declared their area as a “Zone of Peace”, the first in the country ever to be declared as such by the residents composed of some 40 families, and this policy is respected by both rebels and government troops.