Oceanic Rossby waves play a crucial role in shaping the physical and biological dynamics of both open and coastal oceans, especially within the tropical band spanning between the 10°S and 10°N parallels. Yet, the extent to which Rossby waves can transmit and impact the hydrography and ecosystem of semi-enclosed seas like the South China Sea (SCS) remains unclear. This study aims to investigate the transmission of Rossby waves through the Philippine archipelago, using satellite altimeter-derived sea level anomaly (SLA) and coastal tide gauge records. Our findings reveal that westward-propagating Rossby waves in the tropical Pacific Ocean with a wave speed of ~0.64 m s−1 first entered the Celebes Sea, and then passed through the Sibutu Passage into the Sulu Sea from April to December 2017. Subsequently, the waves propagated along the northeast coast of Sabah and the east coast of Palawan before exiting through the Mindoro Strait to the central SCS. Additionally, a β-refracted Rossby wave with wave speed of 0.28 m s−1 also penetrated the archipelago but at a latitude further north ~10°N from July to November via Surigao Strait and propagated toward the south and north of Palawan, ultimately reaching the west coast of Palawan in the eastern central SCS. This study verifies that the transmission of Rossby waves originating from the east of the Philippines could induce intraseasonal sea level oscillations off Palawan, which could subsequently propagate westward across the central SCS as identified in previous field observations.