Abstarct: Abstract The implementation of lateral load-resisting systems in high-rise buildings—particularly against seismic and wind loads—is a fundamental principle in structural engineering design. Although conventional reinforced concrete shear walls exhibit acceptable performance, they suffer from drawbacks such as reduced usable interior space and increased structural weight. On the other hand, steel shear walls are prone to premature buckling under compressive stresses. To address these limitations, a novel composite shear wall system has been introduced, combining the synergistic behavior of concrete and steel to enhance seismic performance. In this system, a steel plate is embedded within a reinforced concrete core. This configuration enables the concrete to restrain early buckling of the steel, while the steel significantly improves the shear strength and ductility of the wall. The present study experimentally investigates the performance of three shear wall specimens: a conventional reinforced concrete wall as the control specimen, and two composite walls incorporating different types of steel plates within the concrete core. The primary distinction between the composite walls lies in the type of steel plate used—one with a flat plate and the other with a perforated plate. The experimental evaluation focused on key seismic parameters, including ultimate strength, stiffness, ductility, and energy dissipation capacity, to assess the relative advantages of the composite system over traditional configurations. Test results demonstrated that the composite walls exhibited superior and more stable seismic performance compared to the control specimen. The flat-plate composite wall achieved an ultimate strength of 147.5 kN, representing a 57.6% increase over the conventional concrete wall (93.6 kN). Meanwhile, the perforated-plate specimen, with an ultimate strength of 127.5 kN, showed enhanced overall behavior due to the mechanical interlocking effect of the perforations. The perforated specimen achieved a ductility ratio of 2.06, improving by 33.8% over the control and 11.4% over the flat-plate specimen. Its hysteretic damping ratio reached 0.17, marking a 30.7% and 13.3% increase compared to the control and flat-plate specimens, respectively. Additional advantages included delayed crack initiation, stiffness retention at higher drift levels, and greater post-peak energy absorption. Despite using less steel, the perforated specimen retained over 80% of the flat-plate wall’s strength while offering higher ductility, making it a cost-effective and efficient alternative for modern lateral load-resisting systems.