Abstract: As a critical natural ecotone and barrier between marine and terrestrial ecosystems, mangrove wetlands play an indispensable role in the capture and sequestration of atmosphere carbon dioxide (CO₂), as well as organic carbon in the marine environment. Carbon within mangrove wetland ecosystems is ultimately fixed through a series of biological processes and biogeochemical reactions and sequestered in three primary and stable forms: vegetation biomass (i.e., plant aboveground and belowground biomass), plant litters (such as leaves, branches and root, etc.), and soil organic carbon (SOC). In contrast, the export and emission of organic carbon from mangrove wetlands occur mainly through three dominant pathways: the fluxes of greenhouse gas (mainly CO₂ released via soil respiration and litter decomposition, and methane (CH₄) produced under anaerobic soil conditions), the feeding and activities of benthic fauna (such as crabs and snails, etc.), and the hydrological export of dissolved organic carbon (DOC) and particulate organic carbon (POC) into adjacent coastal waters via tidal flow and runoff. By synthesizing the research findings reported in relevant domestic and international publications over the past six years (2018—2023), we reviewed the advances in three key processes of mangrove wetland carbon cycling, including carbon sequestration (i.e., carbon storage, carbon density and carbon sequestration rate) and its influencing factors (e.g., plant, soil physical and chemical properties), as well as the main organic carbon processes (i.e., carbon input and carbon export) in the carbon cycle of mangrove wetlands. Based on the review, we propose two urgent scientific and practical issues that need to be addressed in the current ecological restoration of mangrove wetlands. The first issue is the restoration and enhancement of the carbon sink capacity of degraded mangrove wetlands. The second issue is the need to balance the relationship between conservation (which have high and stable carbon sink capacities and should be protected from disturbance) and the ecological restoration of degraded mangrove areas. To address these gaps, future research should: in-depth exploration of the interactive effects of biotic and abiotic factors on mangrove carbon processes; systematic investigation of the transformation mechanisms of carbon pools; quantitative evaluation of the carbon sink benefits of vegetation restoration; detailed evaluation of restoration processes of carbon sinks; research on the priming effects and roles of consumers (e.g., benthic fauna) in carbon dynamics. Our review could provide a scientific support for the protection and restoration of mangrove wetlands, mitigation of greenhouse effect, and achieving the goals of carbon emissions peaking and carbon neutrality.