[Objective] The future land use and land cover change (LULCC) and its impact on ecosystem carbon storage were predicted in order to provide a scientific basis for regional land use decision-making and carbon management. [Methods] Based on the quantitative analysis of 30 m resolution remote sensing images of Hainan Island in 1990, 2000, 2010, and 2020, the spatio-temporal evolution of land use and its impact on carbon storage were analyzed. Combined with geographic information system (GIS) spatial superposition analysis, the spatial patterns and mechanisms of land use changes in coastal zones and the impacts of complex land use changes on tropical and subtropical coastal zones were assessed. The InVEST model was used to estimate carbon storage in Hainan Island’s coastal zone. The estimation was further linked to the GeoSOS-FLUS model to predict the distribution characteristics of multi-scenario land use changes in the study area in 2030, and to analyze the influence mechanism on ecosystem carbon storage under different future scenarios. [Results] ① From 1990 to 2020, the areas of cropland, forest land, grassland, and unused land in the study area decreased, while the areas of water and built-up land increased. Among them, the areas of unused land and cropland consistently decreased every year, while the area of built-up land increased year by year. ② Land use/cover change led to a continuous decrease in carbon storage for the study area, reaching 1.50×10⁶ t with a decline rate of 5.00×10⁴ t/a over the past 30 years. The increase in built-up land and the decline in forestland were the key causes for the decrease in carbon storage. The increase in carbon storage due to the transformation from unused land to grassland was the most significant change, with an increase of 1.25×10⁵ t. On the other hand, the change from grassland to forest land (artificial forest land) was the most prominent cause for the decrease in carbon storage, accounting for a decrease of 5.68×10⁵ t. ③ Predicted carbon storage in the Hainan Island coastal zone based on the FLUS model was evaluated. The accuracy met the research requirements verified by historical data. Among the three prediction scenarios, forestland will be effectively protected by 2030 only under the ecological priority scenario with an increase in area of 11.91 km². Built-up land will increase to different degrees under the three scenarios, and the development priority scenario had the largest increase. [Conclusion] A large area of natural grassland with high carbon density on Hainan Island has transformed into artificial forest land with low carbon density, and the high carbon area has transformed into a low carbon area, which weakened the regional carbon sequestration ability. A series of land use regulation policies should be adopted to increase the proportions of woodland, grassland, and other land types, and to optimize the transformation of regional carbon sources into carbon sinks.