Purpose of this study is to develop a multifunctional theranostic agent for both imaging (MR and fluorescence) and combined therapy (photodynamic and radiotherapy). Initially, manganese oxide nanoparticles (MnO NPs) were synthesized and conjugated with diethylenetriaminepentaacetic acid (DTPA) which will be then called as MnO-DTPA NPs, and at the final step, synthesized MnO NPs were encapsulated with niosomes in the presence of protoporphyrin-IX (PP(IX)). In vitro cell culture and bioaffinity studies were performed on PC-3 and BJ cells. The structures (Niosome-MnO-DTPA-PP(IX)) have fluorescence properties and photodynamic therapy potential due to the presence of PP(IX) as well as MR imaging and photodynamic and radiotherapy efficiency. According to data, it was claimed that toxicity of MnO NPs were significantly decreased after encapsulation of niosomes especially for BJ cell line. Therapy potential of the 'Niosome-MnO-DTPA-PP(IX)' was examined and promising findings were obtained for the potential use of combined therapy agent for prostate cancer cells.