An analytical approach for the nonlinear vibration analysis of imperfect functionally graded carbon nanotube-reinforced composite (FG-CNTRC) cylindrical panels is presented. The FG-CNTRC cylindrical panel is subjected to external pressure in the thermal environment. The nonlinear temperature distribution in the thickness direction is assumed. The classical thin shell theory with the von-Kármán strain-displacement kinematic nonlinearity is employed in the constitutive laws of the shell. The governing equation is solved by utilizing Galerkin’s method in conjunction with the stress function concept. Finally, to find the nonlinear dynamic responses, the fourth order Runge-Kutta method is used. The effect of the four various types of the CNTs distributions, such as UD, FG-Λ, FG-X, and FG-O is considered on the cylindrical panel. The influence of material parameters, initial imperfection, and temperature on the nonlinear vibration response of functionally graded CNTRC cylindrical panel is presented.