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Long-term satellite data (2003-2017) are analyzed to investigate the variability of ocean surface chlorophyll-a (Chl-a) concentration off the Halmahera Island under influence of the Indonesian Australian Monsoon and the El Niño-Southern Oscillation (ENSO). In this study, we first analyzed the seasonal variability of Chl-a, and then describe the relationship between sea surface Chl-a, sea surface temperature (SST), and sea surface wind stress in the region. Our results demonstrate that prevailing northerly and southeasterly wind stresses play a pivotal role in generating Chl-a maxima off the Halmahera Island. On seasonal time scale, the strengthening of northerly and southeasterly wind stresses (up to ~0.01 N m-2) during the Northwest and Southeast Monsoon seasons produce enhanced phytoplankton blooms associated with sea surface cooling (~28.8 °C) in the area of study. On interannual time scale, the largest positive Chl-a and wind stress anomalies and the coolest SST anomaly are observed in 2006 during El Niño event. Meanwhile, the greatest negative Chl-a anomaly is prevailed during the 2016 negative IOD event. This study demonstrates that wind variability is the essential factor in determining the magnitude of Chl-a maxima off the Halmahera Island.