<p>This study investigates torsional wave propagation in a piezoelectric fiber-reinforced composite (PFRC)-layered structure using unified nonlocal surface/interface elasticity. The PFRC is modeled as a composite comprising piezoelectric fibers embedded within an epoxy matrix. Micro-mechanical analyses are conducted to determine the effective material properties of the PFRC using the strength-of-materials (SM) approach and the rule-of-mixtures (RM) technique. The general governing equations are formulated based on the principles of nonlocal electromechanical theory by incorporating an intrinsic material length scale to account for size-dependent effects. Surface effects are introduced through the Gurtin–Murdoch (G-M) surface elasticity model, which is applied to the boundary conditions of the composite structure. The dispersion relation for torsional waves is obtained under non-classical boundary conditions, utilizing the surface/interface theory. Numerical simulations reveal the significant influence of the coupled effects of nonlocality and surface elasticity on the behavior of propagating torsional waves. Parametric studies are conducted to illustrate the impact of nonlocal interactions, surface/interface parameters, fiber volume fractions, and material heterogeneities on the phase velocity and mode shapes of the waves. The findings highlight the critical role of multiscale effects in accurately modeling wave propagation in PFRC structures.</p>