This study presents a finite element analysis (FEA) of bioabsorbable vascular stents fabricated from poly(lactic acid) (PLA) and PLA/graphene nanocomposites to evaluate their mechanical response under physiological loading conditions. A three-dimensional helical-ring stent geometry was modeled and analyzed in COMSOL Multiphysics 6.2 using nonlinear elastic–plastic material behavior. The addition of 1 wt% graphene nanoplatelets (GNPs) was modeled through the Halpin–Tsai relation to estimate the effective modulus enhancement. Simulation results demonstrate that the PLA/graphene nanocomposite stent exhibits superior mechanical performance compared to pure PLA, with a 21.4% reduction in radial displacement, 25.8% lower maximum von Mises stress, 32.4% improvement in radial strength, and 37.2% reduction in recoil. These improvements are attributed to the effective load transfer between the PLA matrix and graphene fillers, resulting in enhanced stiffness and stress uniformity. The findings confirm that graphene reinforcement can significantly improve the structural integrity and fatigue resistance of bioresorbable polymer stents, supporting its potential for next-generation cardiovascular scaffolds. The study introduces a novel integration of the Halpin–Tsai micromechanical model with nonlinear FEA to predict the reinforcement effect of graphene nanoplatelets on PLA-based bioresorbable stents, providing a computational insight rarely reported for polymeric nanocomposite vascular scaffolds.