A novel "ion-imprinting" strategy is introduced for the development of metal sulfide scavengers to achieve highly selective capture of radiocesium (¹³⁷Cs). The study presents a metal sulfide material, Cs₂.₃₃Ga₂.₃₃Sn₁.₆₇S₈·H₂O (FJSM-CGTs), which exhibits an "imprinting effect" on Cs⁺. Upon activation with K⁺, the material transforms into FJSM-KCGTS, which demonstrates exceptional selectivity for Cs⁺ removal, achieving equilibrium within 5 minutes and a maximum adsorption capacity of 246.65 mg g⁻¹. This material effectively captures Cs⁺ in complex environments, even in the presence of competing ions like K⁺, Na⁺, Ca²⁺, Mg²⁺, Sr²⁺, and Eu³⁺. It successfully removes over 99% of ¹³⁷Cs from industrial waste solutions, with a significant reduction in waste volume. The material's performance is confirmed through single-crystal structural analysis and density functional theory (DFT) calculations, which reveal that the "imprinting effect" arises from the spatially confined framework. The study highlights the mechanism of Cs⁺ capture and the structure-function relationships, offering insights for the development of efficient inorganic adsorbents for radionuclide separation. The material is also shown to be recyclable and effective in ion-exchange columns, demonstrating its potential for practical applications in radioactive waste treatment. The results indicate that the "ion-imprinting" strategy significantly enhances the selectivity and efficiency of Cs⁺ capture, making it a promising approach for environmental remediation and nuclear waste management.A novel "ion-imprinting" strategy is introduced for the development of metal sulfide scavengers to achieve highly selective capture of radiocesium (¹³⁷Cs). The study presents a metal sulfide material, Cs₂.₃₃Ga₂.₃₃Sn₁.₆₇S₈·H₂O (FJSM-CGTs), which exhibits an "imprinting effect" on Cs⁺. Upon activation with K⁺, the material transforms into FJSM-KCGTS, which demonstrates exceptional selectivity for Cs⁺ removal, achieving equilibrium within 5 minutes and a maximum adsorption capacity of 246.65 mg g⁻¹. This material effectively captures Cs⁺ in complex environments, even in the presence of competing ions like K⁺, Na⁺, Ca²⁺, Mg²⁺, Sr²⁺, and Eu³⁺. It successfully removes over 99% of ¹³⁷Cs from industrial waste solutions, with a significant reduction in waste volume. The material's performance is confirmed through single-crystal structural analysis and density functional theory (DFT) calculations, which reveal that the "imprinting effect" arises from the spatially confined framework. The study highlights the mechanism of Cs⁺ capture and the structure-function relationships, offering insights for the development of efficient inorganic adsorbents for radionuclide separation. The material is also shown to be recyclable and effective in ion-exchange columns, demonstrating its potential for practical applications in radioactive waste treatment. The results indicate that the "ion-imprinting" strategy significantly enhances the selectivity and efficiency of Cs⁺ capture, making it a promising approach for environmental remediation and nuclear waste management.