Multi-use of offshore wind farms with low-trophic aquaculture could provide sustainable energy, nutritious seafood, and restorative ecosystem services through nutrients and carbon capture and utilization. In a transition zone between marine and brackish seas, our model predicted that allocating 10% of projected wind farm areas to blue mussel and sugar kelp aquaculture in the North Sea - Baltic Sea transition zone could yield 18 t-fresh weight ha−1 yr−1. Total carbon captured and harvested from seaweed biomass and mussel shells would equal 40% of the carbon dioxide emissions from the Danish agricultural sector. Furthermore, global aquaculture production is projected to increase by 132% compared to current production. With technological and regulatory challenges still to be addressed, these findings demonstrate a vast potential of multi-use in offshore areas, which can generate blue biomass with fewer user conflicts, while mitigating eutrophication and climate change, thereby supporting multiple global sustainable development goals.