<p>This paper presents a thermo-mechanical-electro coupling dynamic model for the free and forced vibration analysis of rotating graphene nanoplatelets (GNPs)-reinforced piezoelectric composite microplates subjected to external mechanical and electric loads in thermal environment. Three different GNPs dispersion patterns describe the thickness-wise variations of material properties, which are then evaluated by the extended rule of mixture and Halpin–Tsai micromechanics model. Based on the first-order shear deformation theory (FSDT) and modified couple stress theory (MCST), the governing equations for the rotating piezoelectric composite microplate are established by the Hamilton’s principle, and are subsequently discretized by the Chebyshev-based Galerkin method. The complex mode analysis method is adopted to deal with the free vibration and the four-order Runge–Kutta-Merson’s algorithm is utilized to solve the dynamic responses. The convergence and comparative studies are first carried out to validate the effectiveness of the present method. The effects of load type, damping coefficient, angular velocity, hub radius ratio, small-scale parameter, external voltage, temperature rise as well as the dispersion pattern, weight fraction and piezoelectricity of GNPs on the modal characteristics and dynamic responses of the rotating piezoelectric composite microplates are discussed in detail. The coupling of rotational and deformation motions in the present model demonstrates comprehensive and complicated modal characteristics. The numerical results show that GNPs are the great potential reinforcements for improving the structural stiffness and piezoelectric performance in design of smart piezoelectric composite structures.</p>