The iron oxide nanoparticles (IONPs) have enormous applications in biomedical fields. The change in properties of IONPs such as morphology, size, surface charge, agglomeration, and magnetization have marked impact on their effectiveness. In this work, evaluation of the physico-chemical properties of different green synthesized IONPs compared with their chemical synthesized one has been carried out. IONPs were fabricated chemically (Chem-IONPs) or through a green route using curcumin (Cur-IONPs), aloe Vera (AV-IONPs), and green tea (GT-IONPs) extracts. All prepared IONPs were characterized using transmission electron microscopy (TEM), zeta potential measurements, UV–Vis spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and differential scanning calorimetry (DSC) techniques. Additionally, the DPPH scavenging activity of the prepared nanoparticles was tested. The present study showed in a comparative way the effect of different routes of IONPs synthesis on their physicochemical properties. These different properties may have great usage in different biomedical applications.