In this work, nanocomposites were prepared with different weight ratios based on the formula (1-x)ZnO + (x)Fe3O4, where x = 0.01, 0.03, 0.05, 0.07 and 0.09. The structure, morphology, optical, and magnetic properties were examined by X-ray diffraction, UV VIS-NIR diffuse reflectance spectroscopy, high-resolution transmission electron microscopy (HRTEM), and vibrating sample magnetometer (VSM). The X-ray diffraction (XRD) results confirm the phase purity formation of Fe3O4-ZnO nanocomposites. The transmission electron microscopy (TEM) exhibited the prepared powders are nanoparticles with the spherical shapes of Fe3O4 and nanorod for ZnO. UV VIS-NIR diffuse reflectance measurements showed that the Fe3O4 modified the optical properties of ZnO. Results of the vibrating sample magnetometer (VSM) display a superparamagnetic characteristic of Fe3O4 and ferromagnetic behavior for nanocomposites. The magnetization and remanence magnetization of nanocomposites increases with Fe3O4 content.