The present paper studies buckling and free vibration analyses of sandwich beam. The sandwich beam is composed of a soft core integrated with functionally graded graphene nanoplatelets reinforced composite face sheets. Kinematic relations are developed based on Extended Higher-Order Sandwich Beam Theory (EHSPT). The governing equations are derived using Ritz-Lagrange formulation. The effective mechanical properties of epoxy/GPLs composites are obtained from the Halpin-Tsai micro-mechanical model and rule of mixture. The numerical results are obtained using the Ritz Method. The natural frequencies and buckling loads are obtained in terms of weight fraction and distribution of graphene nanoplatelets, length to thickness ratio, core to surface ratio, and different boundary conditions. Before presentation of complete numerical results, a comparative study is presented to check trueness and correctness of the results. It is concluded that maximum and minimum natural frequencies and critical buckling loads of sandwich nanobeam are obtained for FG-X and FG-O distributions, respectively.