In the present study, a sustainable green chemistry approach was established to fabricate magnetic FeO nanoparticles (FeONPs) using the aqueous fruit extract of edible C. guianensis (CGFE). Synthesized NPs were further confirmed with different high-throughput characterization techniques such as UV-visible spectroscopy, FT-IR, XPS, DLS and zeta potential analysis. Additionally, XRD, AFM, HRTEM and SQUID VSM demonstrate the generation of crystalline CGFeONPs with mean diameter of 17 ± 10 nm. Interestingly, CGFeONPs exhibit a stupendous bactericidal action against different human pathogens which depicts its antimicrobial value. A significant dose-dependent cytotoxic effect of CGFeONPs was noticed against treated human hepatocellular carcinoma cells (HepG2).