Meeting the demand for fresh water and energy is among the major challenges to the development of human civilization. Herein, we report the concept of a covalent organic framework hydrogel (named CPP) as a synergistic platform for seawater desalination and uranium extraction. In natural seawater, CPP shows an exceptional evaporation rate (0.744 kg m −2 h −1 ) and uranium extraction capacity (4.15 mg g −1 ), which benefits from the hydrophilic 3D hydrogel network and capillary microporous channels of CPP providing adequate water transport, improving the mass transfer of uranyl ions, and increasing the binding sites of uranyl ions. In addition, CPP exploits interfacial solar heating to limit heat, increases solar energy utilization, and further accelerates the coordination between uranium and binding sites. The excellent photocatalytic effects endow CPP with high anti-biofouling activity, achieving long-term solar desalination and highly efficient uranium extraction. The connection between freshwater and nuclear energy is realized in a new material providing an opportunity to meet the growing needs of mankind. CPP with capillary microporous channels for rapid diffusion of uranyl ions and adequate water transport, and good photothermal effect can realize synergistic freshwater collection and uranium extraction.