<p>This study presents a comprehensive investigation of the propagation of shear-horizontal (SH) waves in a tri-layered smart composite structure comprising a piezoelectric fiber-reinforced composite (PFRC) layer sandwiched between a fiber-reinforced composite (FRC) layer and a piezoelectric substrate. The novelty of this work lies in the incorporation and analysis of mechanical and electrical interfacial imperfections between the layers, providing a more realistic framework for studying SH wave behavior in multilayered systems. Starting with the constitutive equations for all considered layers, analytical modeling and numerical simulations are employed, with the aid of realistic boundary conditions, to derive the dispersion relation of SH waves under various configurations of interfacial imperfections and thickness ratios. The key contributions of this study include a detailed parametric analysis of the effects of fiber volume fraction, interfacial imperfections, and thickness ratios on the phase velocity of SH wave. The results demonstrate critical trends, such as the significant role of bonding parameters and layer configurations in controlling wave propagation characteristics. The obtained outcomes offer valuable insights for optimizing the design and functionality of advanced engineering applications, including non-destructive testing, structural health monitoring, and energy harvesting devices. The study bridges a gap in the existing literature by providing an analytical framework for SH wave propagation in complex, multi-layered composite systems.</p>