This study examines the vibration response of imperfect functionally graded (FG) cylindrical shells reinforced with different types of eccentrically placed stiffeners. The material composition follows a power-law distribution, varying with different grading indices. The analysis is conducted analytically under simply supported boundary conditions, considering longitudinal and transverse stiffeners of circular, rectangular, and triangular cross-sections. The cylindrical shell, resting on an elastic foundation, is subjected to thermo-mechanical loading. The governing equations are derived using the first-order shear deformation theory, incorporating von Kármán-Donnell nonlinear geometric formulation and the smeared stiffener method. A numerical approach combining the fourth-order Runge-Kutta method and Galerkin's procedure is employed to evaluate the dynamic response and natural frequencies. Results reveal that increasing foundation stiffness enhances natural frequencies by 15% and reduces vibration amplitude. Conversely, elevated temperature leads to a 12% reduction in natural frequencies and a decrease in structural rigidity, highlighting the coupled effects of thermal and mechanical loads on the shell's dynamic behavior.