This study proposes a strategy to develop highly selective adsorbents for radiocesium capture using "ion-imprinting" technology. The researchers synthesized a metal sulfide, Cs2.33Ga2.33Sn1.67S8·H2O (FJSM-CGTS), which exhibits a strong affinity for Cs+ ions. By activating the material with K+, the Cs+ recognition sites are created, leading to a material called FJSM-KCGTS that can achieve rapid and efficient adsorption of Cs+ within 5 minutes, with a maximum adsorption capacity of 246.65 mg·g−1. This material overcomes the challenge of competing ions and effectively captures Cs+ in complex environments. It has been successfully used to treat actual 137Cs-liquid-wastes, achieving removal rates of over 99%. The "ion-imprinting" process was visualized through single-crystal structural analysis, and density functional theory (DFT) calculations confirmed the mechanism behind the selective adsorption. This work demonstrates the potential of inorganic ion-imprinted adsorbents for efficient and selective capture of key radionuclides in environmental remediation and waste disposal.This study proposes a strategy to develop highly selective adsorbents for radiocesium capture using "ion-imprinting" technology. The researchers synthesized a metal sulfide, Cs2.33Ga2.33Sn1.67S8·H2O (FJSM-CGTS), which exhibits a strong affinity for Cs+ ions. By activating the material with K+, the Cs+ recognition sites are created, leading to a material called FJSM-KCGTS that can achieve rapid and efficient adsorption of Cs+ within 5 minutes, with a maximum adsorption capacity of 246.65 mg·g−1. This material overcomes the challenge of competing ions and effectively captures Cs+ in complex environments. It has been successfully used to treat actual 137Cs-liquid-wastes, achieving removal rates of over 99%. The "ion-imprinting" process was visualized through single-crystal structural analysis, and density functional theory (DFT) calculations confirmed the mechanism behind the selective adsorption. This work demonstrates the potential of inorganic ion-imprinted adsorbents for efficient and selective capture of key radionuclides in environmental remediation and waste disposal.