<p>This study aims to investigate the thermo-mechanical buckling behavior of advanced composite sandwich plates in thermal environments, based on high-order shear deformation theory (HSDT), which incorporates anti-tri-chiral auxetic core layers and functional graded material (FGM) face layers. The analyzed FGM sandwich plates are simply supported and subjected to uniform, linear, nonlinear, and sinusoidal temperature increases. It is assumed that the temperature distribution changes only in the thickness direction and remains constant across the plate's planar dimensions. It is accepted that the material properties of the components are temperature-dependent and are continuously graded using a power-law distribution across the thickness. Nickel is used as the metal material, and Al₂O₃ as the ceramic material. Additionally, the metal component is reinforced with 10% graphene. The fundamental equations of motion are derived using Hamilton's principle and solved using the Navier method to determine the thermal buckling resistance of anti-tri-chiral auxetic core FGM sandwich plates. A comprehensive parametric study is conducted for various thermal conditions and material grading indices. The results were compared for temperature-dependent and independent FGMs and validated with existing data in the literature.</p>