<p>Laser cladding has been extensively employed in surface repair of engineering components. However, the combination of cylindrical shells and heterogeneous cladding layers will exacerbate its instability. This study investigated the free vibration characteristics of a composite cylindrical shell fabricated via laser cladding. The interfacial region was idealized as a functionally graded layer with homogeneous mixing, where different interfacial geometries were represented by distinct material volume fraction functions across the thickness. Based on the first-order shear deformation theory (FSDT), and with artificial springs used to simulate boundary conditions, the governing equations for free vibration were derived. The natural frequencies and mode shapes were then determined using the Rayleigh–Ritz method. Comparison with finite element simulations confirmed the accuracy of the proposed model. A comprehensive parametric study was performed to examine the effects of interfacial structure—including shape, depth, and spacing—on the dynamic stiffness of the cylindrical shell. The results revealed that the fundamental frequency of cylindrical shells decreases as the interface layer thickness increases while as the groove spacing decreases. The triangular interface shows the least sensitivity to both interfacial depth and spacing, followed by the arc-shaped interface. An increase in the thickness-to-radius ratio leads to a monotonic increase in shell stiffness under all boundary conditions. Based on this research, it can provide theoretical guidance for the surface repair of weakly rigid structural components.</p>