This thesis presents the development of a novel Variable Stiffness Gripper using bistable metamaterials (B-VSG) to address limitations in current actuator technologies. The primary objective was to design a lightweight VSG that can switch between different stiffness states without requiring energy to maintain them. The design process involved optimizing metamaterials for torsional stiffness and bistability. Finite Element Analysis (FEA) and physical experiments were conducted to predict and validate the mechanical behaviour, dynamic behaviour, and stability of the gripper. The results demonstrated a significant increase in torsional stiffness between bistable states, achieving a stiffness increase of 40.2% with a change of 0.173 Nm/rad. The B-VSG showed reduced complexity and lightweight characteristics compared to existing technologies, though further optimization is needed, particularly in the actuation mechanisms and unit cell design. In conclusion, this research successfully developed a novel, lightweight VSG using bistable metamaterials, proving the feasibility of integrating these materials into robotic actuators. Future work should focus on further improving the metamaterial, enhanced control for stiffness adjustment, and long-term performance tests in real-world conditions.