Coastal ecosystems play a significant role in global climate regulation by capturing and storing atmospheric carbon dioxide. Among these systems, mangroves, salt marshes, and tidal wetlands collectively contribute to what is known as blue carbon. These ecosystems are highly efficient carbon sinks because they store large quantities of organic carbon in their biomass and sediment layers for long periods. Mangrove forests, in particular, are recognized for their high productivity and capacity to trap sediments, which enhances long-term carbon storage. In recent decades, scientific attention toward blue carbon ecosystems has increased due to their potential to mitigate climate change and provide ecosystem services such as shoreline stabilization, biodiversity conservation, and fisheries support. However, coastal development, pollution, and climate-related disturbances threaten the stability of these ecosystems. Understanding the mechanisms that regulate carbon sequestration, sediment accretion, and nutrient cycling in coastal wetlands is therefore essential for designing effective conservation strategies. This review explores the ecological and biogeochemical processes that control carbon accumulation in mangrove ecosystems and other tidal wetlands. It also discusses the influence of climate change, anthropogenic pressures, and policy frameworks aimed at protecting blue carbon reservoirs. The review highlights current scientific knowledge, identifies research gaps, and outlines future directions for sustainable management of coastal carbon sinks.