In this article, a semi-analytical solution is provided to investigate the free vibration characteristics of rotating truncated conical shells surrounded by a Winkler–Pasternak type foundation. It is assumed that the material of the shell is composed of epoxy as matrix and graphene nanoplatelets (GPLs) as reinforcement dispersed in both thickness and length directions of the shell. The shell is modeled based on first-order shear deformation theory and the equivalent mechanical properties are evaluated using the rule of the mixture and the Halpin–Tsai model. The governing equations are derived by implementing Hamilton’s principle incorporating centrifugal acceleration, Coriolis acceleration, and the initial hoop tension. Utilizing trigonometric functions, an analytical solution is presented to solve the governing equations in the circumferential direction and a numerical solution is provided in the longitudinal direction by utilizing differential quadrature method. The convergence and accuracy of the present results are examined with those available in the literature. A parametric study is provided to check the influences of boundary conditions, rotational speed, circumferential wave number, mass fraction and dispersion pattern of the GPLs, and Winkler and shear coefficients of the foundation on the natural frequencies of the shell. It is concluded that an increment in the mass fraction of the GPLs increases the natural frequencies and the GPLs scattering near the inner surface and the small radius of the shell have a higher reinforcing effect.