In this wok, we demonstrated a facile two-step method to directly coat a ZnO nanocrystal layer on the surface of one-dimensional (1D) Fe3O4/C composite microrods to form Fe3O4/C@ZnO core-shell microrods. Firstly, 1D Fe3O4/C composite microrods were successfully synthesized by one-pot magnetic field-induced solvothermal reaction according to our previous work. Sencondly, a uniform ZnO nanocrystal layer was facilely coated onto the 1D Fe3O4/C composite microrods via a modified hydrothermal process at a low temperature (60 °C). Importantly, the size of ZnO nanocrystals and the thickness of coating layer can be easily tuned by varying the concentration of Zn(Ac)2·2H2O in the solution. Further investigation has revealed that the as-prepared core-shell microrods exhibited enhanced photocatalytic activity for the decolorization of photosensitized dyes (Congo red) under visible-light illumination. Moreover, these magnetically separable photocatalysts can be readily recycled by a magnet with virtually no loss in catalytic efficiency. We believe this facile synthesis strategy provides a general and efficient way to synthesize other 1D magnetic nanocomposites for different functional applications.