<p>In this study, the thermomechanical buckling behavior of sandwich smart nanoplates with magneto-electro-elastic surface layers was modeled and examined together with high-order plate theory and nonlocal strain gradient elasticity theory. It consists of a functionally graded material (FGM) metal-ceramic foam structure containing four different foam distributions in the core layer of the sandwich nanoplate. FGM core structure includes pure metal, pure ceramic, pure ceramic–metal and pure metal-cerasssmic combinations. The equations of motion were obtained by Hamilton’s principle as a result of the electro-elastic and magneto-strictive coupling effects, as well as the reflection of thermal loads, spring foundation and shear foundation effects into the energy equations, and the equations of motion were solved by the Navier method. Thermal effects, foundation effects, the effects of electric and magnetic potentials applied to the smart surface layers, and the effects of the properties of the foam structure in the core layer on the thermo-mechanical buckling behavior of the smart sandwich nanoplate have been examined in a broad framework. It is thought that the results of this study will be beneficial in the design and production of smart nano electro-mechanical systems that are intended to operate in high temperature environments. The buckling behavior of the smart plate can be adjusted with the properties of the core layer, the properties of the foundation coefficients and the applied external electric and magnetic potentials for a desired temperature operating environment.</p>