Mangroves play an important role in providing protection for coastal areas and mitigating climate change simultaneously. The mangrove ecosystem is potentially a carbon sink but can also be a significant source of carbon emissions if wrongly managed. Degradation of the mangrove ecosystem occurs globally, including on Dompak Island, Indonesia. This research aimed to determine carbon stock in above-ground and belowground biomass of mangroves on Dompak Island to estimate the carbon loss due to degradation reported. The result shows that carbon stock in mangrove vegetation on Dompak Island ranges from 21.11-82.03 tons C/ha. The degradation of the mangrove ecosystem on Dompak Island was estimated to have caused 983.94-3,823.2 ton/ha carbon loss between 2007-2018. Based on one-way ANOVA analysis, above-ground organic carbon stocks and underground organic carbon stocks between stations were found to be significantly different (p < 0.05).