To overcome the disadvantages of chemical and physical methods, phyto-fabricated nanoparticles attained great attention due to their multifarious applications. Here we successfully demonstrated Papaver somniferum L. mediated green synthesis of lead oxide (PbO) and iron oxide (FeO) nanoparticles. Characterization of nanoparticles involved techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and energy dispersive X-ray (EDX) associated with scanning electron microscopy (SEM). XRD analysis confirmed the phase identification and crystalline nature. FTIR analysis confirmed the capping of nanoparticles by plants' phytochemicals. SEM revealed morphological features of PbO and FeO with size of nanoparticles being 23 ± 11 nm and 38 ± 13 nm, respectively. The elemental composition of the nanoparticles was confirmed by EDX. Both bacterial and fungal isolates showed susceptibility towards PbO and FeO NPs. Both the NPs also showed considerable total antioxidant potential, free radical scavenging potential and reducing power. Insignificant level of α-amylase for both NPs was observed. FeO NPs showed superior biocompatibility with human RBCs as compared to PbO whereas PbO showed more potent anti-cancer activity as compared to FeO NPs. Overall our study concluded that both NPs played vital role in multiple biological assays however, extensive research focused on cytotoxic evaluation of NPs in-vivo is required.