Purpose <p>This study investigates energy harvesting and aeroelastic stability of pinned-free piezo-aeroelastic beams with torsional spring supports, made of functionally graded graphene-reinforced composites (FG-GPL). The goal is to evaluate how graphene content, layer thickness, torsional stiffness, and reinforcement pattern influence flutter, limit cycle oscillations (LCO), and voltage generation.</p> Methods <p>An aeroelastic model for FG-GPL beams in subsonic flow was developed and validated against literature for accurate prediction of flutter velocities and natural frequencies. Parametric studies examined the effects of material composition, layer thickness, spring constants, and layup patterns on flutter onset, dynamic response, and energy harvesting. LCO amplitudes and voltage outputs were calculated under varying flow velocities and structural configurations.</p> Results <p>Increasing graphene content, beam and piezoelectric layer thickness enhanced flutter velocities, frequencies, and dynamic stiffness, improving aeroelastic stability. FG-X layups achieved higher flutter velocities and voltage output, while unidirectional configurations provided greater stability but lower energy conversion. Voltage generation and tip deflection increased beyond the flutter threshold. LCO analysis indicated thinner layers raised voltage sensitivity, whereas optimal thickness maximized energy harvesting. Higher torsional spring constants elevated flutter velocities and frequencies, while lower constants improved energy extraction at higher flow velocities. Reinforcement pattern effects were secondary to thickness and graphene content.</p> Conclusion <p>FG-GPL beams with torsional supports exhibit strong potential for combined vibration control and energy harvesting. Optimizing graphene content, layer thickness, reinforcement pattern, and torsional stiffness balances aeroelastic stability with electrical performance, providing guidance for advanced piezoelectric harvesters in aerospace and structural applications.</p>