Reduction of soluble U(VI) to insoluble U(IV) oxide is an effective approach to control uranium contamination. Three-dimensional (3D) macroporous g-C₃N₄ photocatalyst with interconnected porous was prepared by thermal polymerization and template etching using self-assembly of SiO₂ nanosphere as the template. The material was then applied to adsorption-photocatalytic reduction of U(VI). Characterization results showed that the 3D macroporous g-C₃N₄ photocatalyst presented a well-defined interconnected macroporous architecture and numerous nanopores existed on the well-defined macroporous skeleton. 3D macroporous g-C₃N₄ also had a significant increase in specific surface area which was beneficial to the absorption of visible light. Adsorption results showed that the maximum adsorption capacity of U(VI) on 3D macroporous g-C₃N₄ was ~30.5 mg/g, which was more than ~1.83 times higher than that of bulk g-C₃N₄. The adsorption isotherm matched well with the Langumuir equation. Photocatalytic reduction experiments showed that the 3D macroporous g-C₃N₄ had high photocatalytic activity and good stability with the reduction rate constant of 0.0142 min ^-1, which was ~4.9 times higher than bulk g-C₃N₄ (~0.0024 min ^-1). As the sorption-photocatalytic performance of the sample is excellent, 3D macroporous g-C₃N₄ is a high efficient visible-light-responsive photocatalyst for the removal of U(VI) from radioactive wastewater.