To obtain a floating and magnetically recyclable photocatalyst, nano-scaled Fe3O4 particles are first deposited on the surface of the KH-550 modified cenosphere under a hydrothermal condition. The Fe3O4 coated cenosphere is then loaded with a layer of globular-flower-like SiO2 particles by a precipitation method. The Fe3O4/SiO2 double-layer structured cenosphere is finally immobilized with TiO2 nanoparticles doped with rare earth element Eu3+ to enhance the photoactivity of TiO2 using titanium sulfate, urea, and polyvinylpyrrolidone by a hydrothermal treatment. The as-prepared cenosphere is systematically characterized by various characterization techniques. The properties of photocatalytic degradation of methylene blue dye are also investigated. Results show that after being doped with 0.1% Eu3+ ions in relation to Ti4+ ions, the photocatalytic degradation efficiency for the Fe3O4/SiO2/Eu-doped TiO2 coated cenosphere is significantly improved under both ultraviolet and visible light irradiations. The saturation magnetization of the Fe3O4/SiO2/Eu-doped TiO2 coated cenosphere increases to some degree.