Green synthesis of nanoparticles (NPs) from biological constituents extracts have emerged as potential methods for the fabrication of metallic NPs. In the present study, Cuprous oxides hallow microspheres (Cu2O-HMs) have been synthesized using D. carota pulp waste extract (CPWE). This Cu2O hollow microsphere (Cu2O-HMs) synthesis is environmental friendly, at room temperature. The aqueous copper ions are reduced into Cu2O-NPs, when these ions interact with active reducing constituents of CPWE and very little amount of sodium hydroxide for enhancing rate of reaction. The Cu2O-NPs have been characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Transmission electron microscopy (TEM). XRD measurements contain average size of Cu2O-NPs are approx 12 nm which is responsible to form Cu2O-HMs. UV-VIS spectra show that the surface Plasmon resonance peak of copper is observed at 490 nm. FTIR measurements indicate the presence of different reducing constituents in D. carota extract which is responsible for reducing and capping bioreduced Cu2O-HMs. TEM measurement shows that most Cu2O-HMs are spherical in shape and are responsible to form microsphere and nanotubes. Antibacterial activity of Cu2O-HMs tested on S. aureus shows a comparable zone of inhibition. These interesting results may be applicable for the cost-effective, environmental friendly, surface disinfectant and biomedical fields. Copyright © 2017 VBRI Press.