<p>Herein, a magnetically separable Fe₃O₄/g-C₃N₄/BiOI (FCB) ternary composite was constructed as a visible-light-responsive photocatalyst for uranium decontamination through reduction of aqueous U(VI) to less soluble U(IV). The composite was synthesized via combined co-precipitation and hydrothermal methods. Among the prepared materials, the optimized 45%-FCB exhibited the highest U(VI) removal activity, showing 1.8- and 3.3-fold higher performance than BiOI and g-C₃N₄, respectively. The enhanced activity is associated with improved interfacial charge migration and charge separation in the ternary composite, and the overall behavior is more consistent with a Z-scheme-like charge-transfer pathway. Radical trapping and ESR analyses indicated that superoxide radicals were the major reactive species involved in U(VI) reduction. In addition, the catalyst showed good recyclability and rapid magnetic recovery. This work provides a promising strategy for the development of magnetically recoverable visible-light photocatalysts for uranium-contaminated wastewater treatment.</p> Graphical abstract <p></p>