The Arctic region plays a disproportionate role in the global carbon cycle by acting as a critical sink for atmospheric CO<inf>2</inf>. However, how Arctic air-sea CO<inf>2</inf> fluxes will respond to continued warming regarding their spatial and temporal changes remains poorly understood. Here, using 14 CMIP6 Earth System Models, we find that Arctic CO<inf>2</inf> uptake exhibits nonmonotonic trends over the 21st century, initially increasing and then declining, alongside a pronounced poleward shift in regions with high CO<inf>2</inf> uptake. This shift is driven primarily by sea ice retreat and warming-induced rise in sea surface CO<inf>2</inf> partial pressure (pCO<inf>2</inf>) that decreases air-sea pCO<inf>2</inf> difference, which together lead to seasonally asymmetric changes in regional CO<inf>2</inf> uptake. By the end of the 21st Century, the Polar Sea surpasses the Barents Sea and the Arctic Ocean exceeds the Nordic Seas in CO<inf>2</inf> uptake. These findings indicate the importance of accurately simulating Arctic climate processes to assess future carbon-climate feedbacks and their implications for global climate mitigation.