Propose <p>This study presents a comprehensive analysis of the free vibration behavior of adhesively bonded lap joints in variable-thickness laminated conical-conical shells under various boundary conditions.</p> Methods <p>The analysis is conducted using the First-Order Shear Deformation Theory (FSDT) for the laminated shell model and the Generalized Differential Quadrature Method (GDQM) to solve the governing equations. The effects of composite material types, adhesive properties, boundary conditions, and geometric parameters such as the thickness-to-radius ratio, overlap length-to-shell length ratio, and cone angle variation on the natural frequencies of the structure are thoroughly investigated.</p> Results <p>Numerical results indicate that the natural frequency increases with higher overlap length and adhesive thickness, while boundary conditions significantly influence the structural dynamics.</p> Conclusions <p>A comparison of the results with previous studies demonstrates good agreement, validating the proposed methodology. The findings provide valuable insights for the design and optimization of laminated composite shell structures, particularly in aerospace and mechanical applications where adhesive bonding is commonly utilized.</p>