The current paper investigates the free vibrations of functionally graded porous plates with graphene platelets reinforcement and integrated with two piezoelectric layers on the top and bottom surfaces (PFGP-GPLRC). According to the distribution of pores and graphene platelets, the material properties vary smoothly in the thickness of the substrate. Two types of pore distribution, symmetrical and asymmetrical, combined with two types of graphene distribution, uniform and symmetric, are considered. Based on the assumption that the electric potential energy is distributed linearly in the thickness direction of each piezoelectric layer and that the mechanical displacement components are approximated according to a four-variable refined plate theory (HSDT-4), the governing equation of the hybrid plates is established and then solved by pb-2 Ritz method. The accuracy of the solution is confirmed through comparative examples. Finally, several new numerical investigations are performed to evaluate the influence of geometric parameters, material properties, and boundary conditions on the free vibration characteristics of the PFGP-GPLRC plates with closed and open circuits.