In the present time, fibers are extensively and frequently used, as they are predominantly essential components in many composite materials. Glass fibers, which possess numerous advantages and benefits such as being lightweight, waterproof, insulating, and durable, are commonly used in construction to reinforce the properties of polymers and certain types of concrete. Intensive research has been conducted on this unique composite material to better understand its recovery and recycling. From this perspective, the objective of this study is to advocate an optimal method for recycling fiberglass waste extensively produced by factories, which leads the research contribution to find sustainable solutions. Consequently, a numerical simulation was conducted on the mechanical behavior of loaded sandwich structures based on a core of GFRP waste, and a PVC facesheet under severe bending using the ABAQUS code. The proposed script considers both the adhesion between different plate components and the evaluative behavior of the constituent materials. The efficiency of the proposed model is evident in the alignment between the theoretical and numerical study of strength and deformation prediction through the various obtained results. Undoubtedly, by examining the bending behavior of typical sandwich panels, we were able to observe the optimal valorization of glass fibers’ waste and PVC material through the efficient design of the core.