Selective and effective adsorptive removal of radiocesium is of great importance in terms of nuclear waste management and environmental remediation, but is still challenging because of its radioactive and non-complexing nature. Herein, metal hexacyanoferrates (MHCF, M = Cu, Co, or Ni) modified fibrous chitosan was prepared by multiple sequential adsorption and self-assembly approach, and applied for the selective and effective adsorption of Cs+. The physically supported MHCF in chitosan fibers showed good crystallinity and stability, and the obtained fibrous composite has high specific surface area (18.2–29.4 m2 g−1). Moreover, MHCF crystals endowed the fibrous chitosan-based adsorbent with a high adsorption capacity and selectivity towards Cs+. Its adsorption kinetic and isotherm performance followed the pseudo second-order model and the Sips model. The qm value of three fibrous MHCF/chitosan (M = Cu, Co, or Ni) composites was 24.9–70.3 mg g−1. The fibrous CuHCF/chitosan composite had the highest qm among the three composites. In summary, the modified chitosan can selectively and effectively remove Cs+ from complicated aqueous solutions.