Sulfhydryl magnetic biological bamboo charcoal nanocomposite (BBC@nFe-SH) was prepared by chemical co-precipitation method for the robust capture of As(III) from aqueous solutions. The novel BBC@nFe-SH shows favorable magnetic field strength (83376 A/m), which enables BBC@nFe-SH to be quickly recovered from aqueous solution. The maximum As(III) adsorption capacity is as high as 98.63 mg/g at pH 5.0 and 40 °C, reaching reaction equilibrium within 120 min. Various characterizations (e.g., SEM, FTIR, VSM and XPS) suggest that As(III) prefers to coordinate with surface oxygen groups bonded to the surface. BBC@nFe-SH displayed high stability and recyclability throughout the removal process, which could be easily activated by 1 mol/L NaOH after usage. Thus, the novel BBC@nFe-SH has promising applications for As(III) treatment.