Divilacan [ˌdiviˈlakan], officially the Municipality of Divilacan (Ibanag: Ili nat Divilacan; Ilocano: Ili ti Divilacan; Tagalog/Kasiguranin: Bayan ng Divilacan), is a municipality in the province of Isabela, Philippines. According to the 2024 census, it has a population of 5,871 people.

Divilacan was derived from the native Casiguran Dumagat Agta compound word vilacan, meaning "fish and shell." The word di implies origin. Therefore, Divilacan literally means “where fish and shells abound.”

Divilacan was a former barrio of Tumauini. It became a separate municipality on June 21, 1969, by virtue of Republic Act No. 5776.

On April 12, 2024, the town is declared an insurgency-free municipality from the influence of CPP, NPA, and NDF, along with Maconacon.

On October 24, 2024, Severe Tropical Storm Trami (Kristine) made landfall to this town causing big destruction along with other cities/municipalities.

The town is one of the four coastal municipalities of the province of Isabela facing the Philippine Sea to the east. The town is bounded to the north by Maconacon, Tumauini to the west, Ilagan to the southwest, Palanan to the south and the Philippine Sea to the east.

Divilacan is situated 101.30 kilometres (62.94 mi) from the provincial capital Ilagan, and 526.89 kilometres (327.39 mi) from the country's capital city of Manila, via Ilagan–Divilacan Road.

Divilacan is politically subdivided into 12 barangays.  Each barangay consists of puroks while some have sitios.