Zamboanga Peninsula is both a peninsula and an administrative region on that peninsula in the Philippines.

The region

Designated as Region IX, Zamboanga Peninsula consists of three provinces, namely, Zamboanga del Norte, Zamboanga del Sur, and Zamboanga Sibugay. The region of Zamboanga Peninsula was previously known as Western Mindanao before the enactment of Executive Order No. 36 on September 19, 2001.

Zambaoanga Peninsula has five cities: Dipolog City, Dapitan City , Isabela City, Pagadian City, and Zamboanga City. Isabela City is actually part of the island-province of Basilan to the south of the peninsula, and is that province's capital. The residents of Basilan opted to join the Autonomous Region in Muslim Mindanao (ARMM) in a recent plebiscite. However, the citizens of Isabela City did not want to join ARMM and so the city was made a part of the Zamboanga Peninsula region with the enactment of Executive Order No. 36 (the same E.O. that renamed the region).

The physical landform

Zamboanga Peninsula consists of the territory of the three Zamboanga provinces plus Misamis Occidental. The peninsula is connected to the main part of Mindanao through an isthmus situated between Panquil Bay and Pagadian Bay . The boundary between the peninsula and the mainland is artificially marked by the border between Zamboanga del Sur and Lanao del Norte.

Zamboanga Peninsula lies between the Moro Gulf, part of the Celebes Sea, and the Sulu Sea. Along the shores of the peninsula are numerous bays and islands.