We synthesized Fe3O4/ZnO core-shell structure as a multifunctional platform for photodynamic therapy (PDT). The magnetic properties of these nanostructures will enable magnetically driven targeting as well delivery of photosensitizer deep in tumor tissues. Reactive oxygen species (ROS) generation capability of ZnO will help to kill cancer cells through oxidative stress. Fe3O4/ZnO core-shell nanostructures were synthesized via a simple method in aqueous phase. X-ray diffraction (XRD) patterns showed the presence of both, Fe3O4 and ZnO phases that suggests the development of a core-shell. Photoluminescence (PL) measurements displayed the excitonic emission of ZnO, at around 380 nm, in co-existence with a weak and broad defect- related green emission. Energy Dispersive X-ray Spectroscopy (EDS) indicated the presence Zn species on the crystal surface at variable amounts, which were dependent on the shell thickness. The generation of singlet oxygen species under UV irradiation has been verified using DPBF (1,3-diphenylisobenzofuran) as quencher for singlet oxygen. Quantum yield (QY) of singlet oxygen generated by core-shell nanoparticles was found to be 28%, suggesting the potential application of these core-shell nanostructures in PDT.