Abstract: Development of marine carbon sinks has become an important way to mitigate climate warming. Among them, mariculture has great potential for “carbon neutrality”. To evaluate the removal carbon sink capacity of mariculture shellfish and macroalgae, the present study calculated the quality and value of carbon sinks, based on mariculture production of shellfish and macroalgae in China coastal provinces from 2004 to 2021. On this basis, we analyzed the temporal and spatial characteristics of the carbon sink quality and estimated the potential carbon sink of mariculture shellfish and macroalgae in future. Results showed that the average annual carbon sink quality was about 1.5388 million tons from 2004 to 2021. The average carbon sink value was about 451 million yuan. Mann-Kendall test and Sen slope estimated that the carbon sink qualities of national mariculture shellfish and macroalgae increased significantly, and the potential carbon sink of shellfish and macroalgae would increase greatly in China. To elevate the carbon sink qualities of mariculture shellfish and macroalgae, countermeasures proposed included in-depth research on carbon sink measurement methods, optimization of mariculture structure, and promotion of ecological service of mariculture carbon sinks with compensation. These suggestions may achieve the maximum ecological, economic and social benefits of mariculture shellfish and macroalgae in future.