<p>The microwave absorption performance of a silicone-based nanocomposite incorporating graphene nanopowders and iron oxide nanoparticles (Fe₃O₄ NPs) was investigated. The Fe₃O₄ NPs were green-synthesized using an aqueous extract of Vitis vinifera fruit. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDS) spectrometer, and transmission electron microscopy (TEM). A crystalline Fe₃O₄ NPs structure was confirmed for the final product by X-ray diffraction, while the presence of different functional groups was indicated by the FTIR spectrum. In the FESEM images, a nearly spherical morphology with agglomeration was observed. A network of randomly oriented spherical Fe₃O₄ NPs, with an average size of 35 nm, was revealed by TEM. For this research, the green-synthesized Fe₃O₄ NPs and graphene nanopowders were dispersed within a silicone matrix to form a nanocomposite, which was designed to enhance electromagnetic wave attenuation through dielectric and magnetic loss mechanisms. The microwave absorption properties of the prepared nanocomposites were evaluated using reflection loss (RL) measurements. The results improved electromagnetic wave absorption performance due to synergistic interaction between graphene and Fe₃O₄ NPs within the silicone matrix. These findings indicate that the green-synthesized Fe₃O₄ NPs, combined with graphene nanopowders, are promising fillers for lightweight microwave-absorbing silicone-based composites.</p>