For the first time, cuprous oxide nanocubes (Cu2O NCBs) were successfully combined with chitosan nanoparticles (CS NPs) to generate Cu2O NCBs/CS NPs composites 15 material with highly optical property and photocatalytic activity using a simple and ecofriendly synthetic approach at room temperature for 30 min. The synthesized Cu2O NCBs/CS NPs were characterized by Ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X – ray Diffraction (XRD), Transmission Electron Microscope (TEM) and Energy-dispersive X-ray spectroscopy (EDX). Results show that the Cu2O NCBs/CS NPs composites possessed an average particle size of 21 ~3-5 nm; in which, Cu2O had the form of nanocubes with a size of ~3-4 nm and CS NPs had spherical shape with a size of ~4-5 nm. In addition, the composition percentages of elements presented in Cu2O NCBs/CS NPs composites material were: Cu (23.99%), O (38.18%), and C (33.61%). Moreover, Cu2O NCBs/CS NPs composites material was also investigated for photocatalytic activity applied in p-nitrophenol degradation. The obtained results showed that the catalytic capability of Cu2O NCBs/CS NPs for p27 nitrophenol reduction reached the highest efficiency of >55% in the treatment time of 25 min, and this efficiency was higher than that of the ZnO@chitosan nanoparticles catalyst under the same conditions.