This work provides a sustainable method for producing iron oxide nanoparticles (FeONPs) using an extract from Amorphophallus paeoniifolius (AP) tubers. The nanoparticles were then thoroughly characterized by TGA/DSC, UV, FTIR, and SEM examination. They demonstrated their strong antibacterial properties against Gram-positive and Gram-negative microbes. The sizes of the ZOI were found to be 19, 25, 16 and 14 at 100 mg/mL as compared to cefoxitin as 18, 23, 8 and 12 mm for Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), Bacillus subtilis (B. subtils) and Staphylococcus aureus (S. aureus) respectively. Their interaction with 2,2-diphenylpicrylhydrazyl (DPPH) revealed their free radical scavenging up to 70 %. NPs at 260 nm (λmax) have shown a hypo-chromic effect in the spectrophotometric approach, suggesting that FeONPs are intercalating in nature. The fluorescence quenching tests indicated the development of a non-fluorescent complex, implying FeONPs interaction with human serum albumin (HSA). As per Scatchard parameters, five binding sites observed in HSA during the interaction with FeONPs, where the Kb value indicated the NPs strong binding strength. The HSA and DPPH interaction nature of FeONPs suggests that they might be helpful in medical applications.