This research quantified the annual gross primary productivity (GPP) dynamics of Bali's two largest mangrove areas, the Ngurah Rai Grand Forest Park (Tahura Ngurah Rai) and the West Bali National Park (TNBB), from 2019 to 2024. Using the Vegetation Photosynthesis Model (VPM) in Google Earth Engine with Sentinel-2A, MODIS LST, and ERA5 data, we produced a high-resolution carbon assimilation baseline. The findings reveal a strengthening photosynthetic uptake, with a province-wide mean GPP near 3.6 kg C m-2 yr-1 and a peak in 2023. Site-level productivity increased by 11.0% at Tahura Ngurah Rai and 7.4% at TNBB. Spatially, GPP diverged significantly: interior, protected canopies were highly productive (averaging > 4.3 kg C m-2 yr-1) and stable, whereas disturbed edge zones, such as near the Suwung landfill in Tahura Ngurah Rai, exhibited low GPP (mean 2.7 kg C m-2 yr-1) and high variability (12.8% CV). These results highlight clear management priorities: preserving high-GPP interior stands and restoring vulnerable edge zones. This high-resolution monitoring provides an actionable baseline for Bali's blue carbon strategies, contributing critical data on ecosystem function for a globally significant tourist and ecological region.