The fabrication of yolk/shell spheres consisting of a movable magnetic core and a chitosan-derived porous carbon shell, and plenty of tiny copper_coresilver_shell nanoparticles confined within the porous shell, is reported. Fe₃O₄ nanoclusters were first synthesized through a solvothermal method and then SiO₂ shell was coated on the Fe₃O₄ surface via a sol–gel process. Subsequently, chitosan was used to modify the surface of Fe₃O₄@SiO₂. Then, selective etching of the middle SiO₂ layer was accomplished to obtain the yolk/shell Fe₃O₄@chitosan composites. Material consisting of copper_coresilver_shell nanoparticles immobilized on each yolk/shell Fe₃O₄@chitosan-derived carbon nanoparticle could be synthesized starting with copper_coresilver_shell nanoparticle–yolk/shell Fe₃O₄@chitosan composite; this is possible due to the well-known strong affinity of chitosan for transition metals. The ensuing catalyst was employed for the epoxidation reaction in aqueous media at ambient temperature. The products were obtained in high yields with the use of low amounts of the catalyst.