<p>The biaxial wrinkling analysis of soft-core functionally graded graphene platelets (GPL)-reinforced nanocomposite sandwich plates was investigated for first time. Five different GPL distribution patterns were assumed for functionally graded (FG) facesheets. An advanced third-order three-layer theory was applied for precise modeling of the plate. The sandwich plate was divided to three layers including two facesheets and a core; each layer is governed by a distinct third-order kinematic assumption. The transverse flexibility of each layer, alongside the displacements, conditions ensuring zero transverse stresses and continuity of transverse stresses were taken into account throughout the entire structure. Using the principle of minimum potential energy, the governing equations were derived and the corresponding closed-form solutions were provided for simply supported boundary conditions. The impact of the plate’s geometry, the materials properties and FG graded patterns on the wrinkling force was thoroughly examined. Moreover, a 3D finite element method (FEM) was employed to perform the wrinkling problem. Results for specific cases were compared with those in existing literature and the present FE model, confirming the accuracy of the proposed theory and findings. The results indicated that increasing the GPL content increases the wrinkling force and wrinkling is not happened in thin sandwich plates. Furthermore, it can be found that increasing the plate thickness increases the wrinkling force, and the O-FG and X-FG patterns have the lowest and highest wrinkling forces, respectively.</p>