EOS-06 OCM-3 observations reveal a distinct seasonal evolution, intensification and spatial migration of the winter phytoplankton bloom over the Arabian Sea, with bloom initiation occurring in January. The bloom progressively intensifies and expands during February–April, extending from the northern Arabian Sea towards the central and southern regions, approximately from 25°N to 10°N. During this period, pronounced mesoscale eddies, with spatial scales of ~100–200 km, are evident and appear to play an important role in modulating bloom distribution through mesoscale transport, vertical nutrient supply and associated physical–biological interactions. From May onwards, the bloom gradually weakens over the Arabian Sea, while the residual high-chlorophyll waters progressively retreat towards the northern Arabian Sea and subsequently extend into the Persian Gulf by late May to mid-June. The high-temporal-resolution OCM-3 observations provide an excellent framework for resolving the initiation, progression, intensification, peak, recession and spatial migration of the winter bloom and for investigating its coupling with mesoscale circulation, nutrient dynamics, atmospheric forcing and seasonal oceanographic variability.