This study used in situ and multisensor satellite data and combinations of various primary productivity (PP) and surface nitrate models to assess the contributions of upwelling and atmospheric deposition to modulating PP in the eastern tropical Indian Ocean (ETIO) during positive phases of the Indian Ocean Dipole (+IOD). Surprisingly, atmospheric deposition of nutrients from wildfires accounted for a higher portion of enhanced PP during +IODs than wind-driven nutrient upwelling. Substantial atmospheric nutrient deposition likely also maintains high PP postupwelling and postwildfire. Multiple regression analysis further supported the importance of atmospheric deposition in determining ETIO PP with a significantly large partial regression coefficient for aerosol optical thickness. It is possible that aerosols from major wildfire areas worldwide contribute nutrients that also nontrivially modulate PP in the oceans’ main upwelling systems.