Carbon neutrality is a crucial strategy for combating global warming, and negative emissions technologies are key to achieving this goal. As the largest carbon reservoir on Earth, the ocean plays an irreplaceable role in regulating global carbon cycling and holds significant potential for negative emissions. Ocean alkalinity enhancement is a highly efficient and ecologically beneficial negative emissions technology. This technology increases ocean alkalinity by adding alkaline minerals to seawater, thereby enhancing the absorption of atmospheric CO₂ and improving the buffer capacity to resist ocean acidification. This study introduces the mechanisms and advancements in ocean alkalinity enhancement research at multiple scales based on the dissolution theory of carbonates in the ocean. Assessing the potential for negative emissions and associated costs reveals several challenges regarding implementation pathways, environmental impacts, and public acceptance. Considering the specific conditions of China’s coastal regions and the characteristics of ocean alkalinity enhancement technology, this study proposes a pathway integrated with wastewater treatment plants and coastal engineering. Furthermore, it provides an innovative concept on the application of ocean alkalinity enhancement and enriches the scientific understanding of blue carbon sinks.