This study investigates the vibration characteristics of pyramid lattice core sandwich panels composed of functionally graded (FG) carbon nanotube-reinforced composites (FG-CNTRC) and FG porous materials under simply supported boundary conditions. A higher-order shear deformation theory (HSDT) based on the energy principle derives the governing equations and boundary conditions using Hamilton’s principle and Navier’s solution technique. Furthermore, a formula is developed to determine the natural frequencies of sandwich plates with simply supported boundaries. The validity and accuracy of the current theoretical model were verified by comparing its results with those reported in existing literature. Additionally, the effects of various porosity distributions, porosity coefficients, carbon nanotube (CNT) distribution patterns, CNT volume fractions and geometric parameters on the vibration characteristics of sandwich plates are examined. Research findings indicate that by adjusting these parameters along with the porosity distribution and carbon nanotube dispersion pattern, the natural frequency during vibration can be effectively controlled.