The ecological and socio-economic services that deltas provide are central to regional infrastructure, sustainable development and climate-change adaptation strategies. Approximately 45% of the global deltaic population resides within South and Southeast Asian mega-deltas. The two principal Vietnamese deltas (Mekong and Song Hong/Red River) account for almost half of that total and have been the subject to sedimentological, hydrogeological and seismic research. However, some inconsistencies remain. Analysis of tidal notches provides an independent, complementary dataset for studying relative sea-level change and associated processes. We present a Late Pleistocene–Late Holocene inundation chronology for the Red River Delta. Pleistocene dates (52–29 cal. kBP) are cautiously attributed to late phases of the Vinh Phuc transgression. Periods of sea-level stabilisation are confirmed leading up to, during and after the Dong Da/Flandrian transgression (6–4 cal. kBP). Results highlight the complexity of past sea-level change in tropical deltaic settings and the value of palaeoecological records to capture sea-level dynamics outside the reach of modern instrumentation. Potential linkage between relative sea level and variability in the strength of the Asian Summer Monsoon/El Niño-La Niña system is posited. Coupling of sea-level regression to climate conditions during the 4.2 and 2.8 ka Cold Events in particular warrants further investigation.