The present research describes a rapid, green, and convenient method for bio-stimulated preparation of silver and iron oxide nanoparticles using the aqueous leaf extract of Psidium guajava Linn (PG). The physicochemical properties of bio-synthesized nanoparticles were determined through UV/Visible, SEM, EDX, and FTIR spectroscopic techniques. The wavelength maxima (nm) at 435 and 300 depict silver and iron oxide nanoparticles' formation, respectively. Scanning electron microscopic analysis infers the spherically shaped silver (81.4-102 nm) and iron oxide (80.3-99.1 nm) particles. The energy dispersive X-ray technique accomplished elemental mapping. The in vitro antioxidant properties of silver and iron oxide nanoparticles were assessed using 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical method with IC50 values of 85.39±0.28 and 78.6±0.63, respectively. The antimicrobial potential was evaluated against selected Gram-positive and Gram-negative bacterial and fungal strains by the agar well diffusion method. The significant zone of inhibition against microbial pathogens reveals the potential industrial and biomedical applications of obtained nanoparticles. The antimicrobial prospective of guava extract-coated iron oxide nanoparticles has been studied for the first time against Bacillus pumilus, Streptococcus faecalis, Streptococcus pneumoniae, and Candida albican. The current report envisions the comparative evaluation of these nanoparticles' antimicrobial and antioxidant characteristics for the first time from this plant.