O
- (Province of Quezon) Olongtao
- (Province of Cavite) Osorio
- (Province of Cavite) Okno
- (Province of Quezon) Ongo
- (Province of Laguna) Oobi
- (Province of Quezon) Oboob
- (Province of Rizal) Ogongo
- (Province of Batangas) Olicasto
- (Province of Laguna) Olla
- (Province of Rizal) Our Lady of Lourdes
- (Province of Quezon) Olongtauo Ilaya
- (Province of Quezon) Olontano
- (Province of Batangas) Olo-olo
- (Province of Quezon) Opias
- (Province of Laguna) Oples
- (Province of Laguna) Oples
- (Province of Quezon) Orista Island
- (Province of Quezon) Osmeña
- (Province of Quezon) Owak