Before its creation as a municipality, Ambaguio was then a barrio of the Municipality of Bayombong. Leonardo B. Perez, then Congressman of Nueva Vizcaya, authored the bill seeking for the creation of Ambaguio as an independent municipality. The bill was approved on 18 June 1966 by virtue of Republic Act. No. 4735. In the same year, Mr. Mariano L. Agnahe, the then Incumbent Barrio Lieutenant, was appointed as the first mayor of the town.
