<p>This study presents a low-cost thin-film fabrication technique for the synthesis of polymer-based composites. Various graphene/PLA composites were prepared at different concentrations. Comprehensive analysis using X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed that the graphene filler acted as a nucleating agent, increasing PLA’s crystallinity initially. Fourier transform infrared spectroscopy (FTIR) revealed the physical interaction between graphene and PLA, while UV–visible spectroscopy demonstrated a decline in transmittance with higher graphene content and enhanced UV blockage. The thermal stability showed an obvious improvement with an increase in the filler content. The optimal graphene content enhances the mechanical properties (elongation at break and tensile strength) of the composites. Moreover, the conductivity, absorption coefficient, refractive index, reflectivity, and dielectric response were modified by the desired filler loading. Moreover, using density functional theory (DFT), the energy bandgaps were observed to decrease with increasing graphene content. This study establishes clear structure–property relationships and identifies the optimal graphene loading for specific applications, particularly in packaging materials that require balanced mechanical and thermal properties. These findings will contribute to the development of sustainable high-performance materials that maintain PLA’s environmental benefits of PLA.</p> Graphical abstract <p>Preparation procedure of graphite/PLA composite materials</p> <p></p>