Titanium dioxide (TiO₂) and reduced graphene oxide (r-GO) were synthesized separately by the radio frequency reactive magnetron sputtering technique on a Si-substrate (TiO₂/Si) and the improved Hummers method, respectively. For deposition of r-GO onto TiO₂, an aqueous solution of r-GO was deposited on the TiO₂/Si thin film by the spin coating process to fabricate the (r-GO/TiO₂)/Si composite thin-film. The (r-GO/TiO₂)/Si composite thin-film is characterized using different spectroscopic techniques to study the effects at the interface of TiO₂ and r-GO in the surface defects, vacancy, incorporation of the different oxygenated moiety, microstructural, surface morphological, electronic, and magnetic performance. Our motivation is to contribute and understand mainly the tuning of the electronic structure and magnetic performance of the (r-GO/TiO₂)/Si composite structure for the development of future promising optoelectronic and spintronic applications. We found that the magnetic performance is improved due to the change in the electronic properties of r-GO deposited on TiO₂ thin films. Thus, the role of the interfacial defects in the (r-GO/TiO₂)/Si thin film and the mechanism of the tuning of the electronic structure and magnetic performance are elucidated comprehensively.