Mangrove ecosystems are critical blue carbon sinks, yet site-specific data on their functional capacity remain limited in the Philippines. This study quantified the biomass, soil organic carbon (SOC), and total ecosystem carbon stock of natural (Aras-asan) and rehabilitated (Poblacion) mangrove stands in Cagwait, Surigao del Sur. Using a stratified random sampling design, forest inventories, species-specific allometric equations, and spectrophotometric soil analysis (100 cm depth), the study assessed ecosystem carbon allocation. Results revealed that the rehabilitated stand exhibited significantly higher total vegetative biomass (71.38 ± 3.85 t/ha) and vegetative carbon stock (35.69 ± 1.93 t C/ha) compared to the natural stand (59.44 ± 5.32 t/ha and 29.72 ± 2.66 t C/ha, respectively; p < .001). However, the natural stand contained a greater total ecosystem carbon volume (984.44 t C/ha versus 952.97 t C/ha) due to immense subterranean reserves. Strikingly, SOC averaged 845 t C/ha across both sites, constituting an overwhelming 96.62% of the total ecosystem carbon stock. The total carbon dioxide equivalent (CO2e) sequestered averaged 3,555.17 t CO2e/ha, presenting a potential high-end voluntary carbon market valuation exceeding $250,000 per hectare. These findings validate the rapid vegetative sequestration efficacy of active mangrove rehabilitation while emphatically highlighting that the strict preservation of undisturbed anaerobic substrate is paramount for preventing catastrophic greenhouse gas emissions. Ultimately, this data provides a robust quantitative baseline to integrate localized coastal wetlands into broader climate finance mechanisms.