The West Philippine Sea, the largest tectonic unit on the Philippine Sea Plate, remains a subject of debate regarding its origin. This article investigates its origin using isotopic dating of submarine drilling core samples. The research reveals that the age range of 93 detrital zircons from the drilling core spans from 2759 to 31 Ma. Except for 3 young zircons related to Cenozoic seafloor spreading of the West Philippine Basin, over 95% of the ages predate the Cenozoic. This suggests that most of the debris originated from older, pre- existing rock units located on the continental margin rather than within an intra- oceanic arc. A significant proportion of Proterozoic- Archean ages and Lu- Hf model ages indicate the existence of recycled ancient continental crust material. The rare earth element distribution pattern and formation environment diagrams of zircons further support a continental crust source. The zircon age spectrum shows several peaks at 2532, 2022, 1500, 792, 426, and 210 Ma. These peaks closely resemble the age spectrum of the Gondwana continent, indicating that the West Philippine Sea (proto- Philippine Sea Block) may have originated from the northeastern edge of Australia on the East Gondwana continent. With the opening of the Neo- Tethys Ocean, the proto- Philippine Sea Block (including the Daito Ridge region, the Gagua Ridge, the East Philippine terranes, and the Hamahira- Waigeo terranes) rapidly drifted northward after splitting from the northern edge of Australia. Subsequently, the opening of the West Philippine Sea Basin led to the fragmentation of this block, with its components now located in the Daito Ridge region to the north, the Gagua Ridge to the west, the Hamahira- Waigeo Islands to the south, and the Luzon- Samar- Mindanao region in the East Philippines. This study provides critical evidence for better understanding the plate tectonic patterns and evolution of the Southeast Asia- Western Pacific region.