Micro/nanospheres have been intensively investigated recently because of their attractive applications. While long reaction times, harsh reaction conditions or multiple steps are generally required for the effective synthesis of ferrites, in this study, Ca0.15Fe2.85O4 microspheres were successfully fabricated via a facile one-pot solvothermal method, utilizing polyethylene glycol as a surfactant. XRD, HRTEM, and SEM analysis revealed that the Ca0.15Fe2.85O4 microspheres prepared were monodisperse in nature, with uniform diameters of about 450 nm and porous interior structure. The Ca0.15Fe2.85O4 microspheres exhibited a clear absorption capacity in the visible light region and the band-gap energy was about 1.95 eV. Furthermore, photovoltaic response of the Ca0.15Fe2.85O4 microspheres was shown in the UV-Visible spectral region, due to the effective photo-induced charge carrier separation. The Ca0.15Fe2.85O4 microspheres may find potential applications in many fields, such as photocatalysis, photovoltaics, sensors, optical, and biomedical devices.