Marine biological activities make substantial influences on aerosol composition and properties. The eastern China seas are highly productive with significant emissions of biogenic substances. Air mass exposure to chlorophyll a (AEC) can be used to indicate the influence of biogenic source on the atmosphere to a certain degree. In this study, the 12-year (2009–2020) daily AEC were calculated over the eastern China seas showing the spatial and seasonal patterns of marine biogenic influence intensity are co-controlled by surface phytoplankton biomass and boundary layer height. The AEC was linearly correlated with aerosol methanesulfonate (MSA) in each of three sub-regions, and the constructed parameterization scheme was applied to simulate the spatiotemporal variation of marine biogenic MSA. This AEC-based approach with observation constraints provides a new insight into the distribution of marine biogenic aerosols which may become increasingly important with the decline of terrestrial input to the studied region.