The study concerns the valorization of Moroccan saffron by-products in the synthesis of metallic oxide nanoparticles. Cerium oxide nanoparticles (CeO2 NPs) were synthesized in an environmentally friendly process using an aqueous extract of saffron by-products. The characterization of the CeO2 NPs and the investigation of their scavenging activity of free radicals using 2-diphenyl-1-picrylhydrazyl (DPPH) method, as well as their antibacterial activity with regard to their application in food products have been studied. The Fourier-transformed infrared spectroscopy (FTIR) analysis confirmed that the active compounds of saffron pruned flowers extracts were involved in the reduction and stabilization of CeO2 NPs. Scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis revealed the homogeneous distribution and the crystalline form of CeO2 NPs, respectively. Moreover, the green CeO2 NPs showed high inhibition percentages (72 %) and strong growth inhibition of the majority of pathogenic bacteria tested, with inhibition zone diameters ranging from 2 to 5 mm.