Among the various radioactive materials, Cesium is a major source of radioactive contamination and known to be the most dangerous radioactive material, can cause enormous damage to the ecosystem environment when released into the environment. Prussian Blue (PB) has been used as an adsorbent to effectively remove cesium, however it has the problem of being difficult to separate in water. In this study, carbonyl iron (CI) which is known as ferromagnetic synthesized with precursor of PB (FeCl₃ and potassium ferricyanide) to solve the problem of PB particles. Adsorption isotherm experiments were also conducted to evaluate the cesium removal ability of the manufactured novel composites. The results obtained in the present study indicate that the novel composite has a cesium removal rate of 99.88% and a distribution coefficient value of 124,900 mL/g. Adsorption behavior follows Langmuir isotherms and the maximum adsorption amount is (qm) 79.3 mg/g. In conclusion, Nano-sized Prussian blue with carbonyl Iron prepared through this study has excellent cesium removal capacity, and it can be completely separated from water when used directly in the cesium treatment field.