The rapid development of the nuclear industry brings benefits for global economic development and solves the energy crisis. However, nuclear industrial activities produce a large amount of radioactive wastewater, which poses serious threats to environmental safety and human health, and ¹³⁷Cs is considered one of the most abundant radionuclides in radioactive wastewater. In this study, we fabricated a new type of ferric ferrocyanide (Prussian blue, PB) functionalized graphene hydrogel (PB/rGOH) for Cs(I) removal. The as-prepared PB/rGOH shows a three dimensional network with PB nanoparticles uniformly distributed on the surface of the rGO sheets. The PB/rGOH could be readily separated from aqueous solution. Moreover, the volume of the composite could shrink to a small stiff bulk material, further reducing the volume of the waste. Kinetics experiments showed that Cs(I) adsorption on PB/rGOH fitted well with pseudo-second-order kinetic model, and the equilibrium data agreed well with the Langmuir model. As calculated from the Langmuir model, the maximum adsorption capacity at pH 5.0 is 58.82 mg g⁻¹. The increase of pH from 3 to 7 could enhance the adsorption capacity, however, further increasing the pH value resulted in serious decomposition of PB nanoparticles. In conclusion, the PB/rGOH prepared in our work showed good performance on removal of Cs(I) in aqueous solution, and has a good application prospect in radioactive waste water treatment.