Dense water on the Antarctic shelves is expected to drive the transport of carbon in the deep Southern Ocean via the formation of Antarctic Bottom Water. However, little is known about its role in enhancing the sequestration of dissolved organic carbon (DOC). In the present study, we examined DOC, dissolved black carbon (DBC), and particulate organic carbon (POC) across the water column in the northwestern Weddell Sea to reveal the influence of the Weddell Sea deep water on DOC transport during its flowing out of the Weddell Sea and descending to the deep Scotia Sea. High DOC concentrations (>60 μmol/L) and low DBC/DOC ratios (<1.5%) were observed in surface water near the South Orkney Islands, ascribing to the sea ice melt-induced phytoplankton bloom as was supported by the linear relation between the POC concentration and salinity. Interestingly, elevated DOC concentrations were observed in bottom water and were positively correlated with POC in surface water, indicating the coupling of surficial primary production and bottom DOC, mechanically via a quick sinking of organic detritus and subsequently solubilization in bottom water and/or surficial sediment. Based on a preliminary estimation, we find that the outflow of Weddell Sea deep water carries 6.3±2.8 Tg/yr of excess DOC (relative to the circumpolar deep water) to the deep Scotia Sea, representing an important source of DOC to the deep Southern Ocean. These results highlight the Antarctic continental shelf pump played a key role in carbon sequestration.