<p>Functionally graded material (FGM) circular plates of variable thickness supported on an elastic foundation represent a structurally efficient solution widely adopted in demanding engineering systems including space vehicles, aircraft, turbine blades, nuclear power plants, combustion chambers, and military armor, wherein the graded material composition coupled with thickness variation ensures optimal stress distribution and weight reduction, while the elastic foundation imparts enhanced restoring force and thermal stability to the structure. In the present study, the axisymmetric thermal buckling analysis of FGM circular plates with exponentially varying thickness in the radial direction, resting on a Winkler-Pasternak elastic foundation and subjected to uniform, linear, and nonlinear temperature profiles through the thickness is presented. The material properties are graded in the thickness direction following a power-law distribution. The governing equations are formulated based on the first-order shear deformation theory (FSDT) combined with von Kármán geometric nonlinearity. Further, these equations are discretized utilizing the harmonic differential quadrature (HDQ) method, considering clamped and simply supported boundary conditions. The obtained results are validated through comparison with previously published studies based on different methods and theories, demonstrating excellent agreement and confirming the accuracy of the present formulation. The influence of foundation stiffness, thickness variation and material gradation on thermal buckling behavior under various boundary conditions is analyzed. Three-dimensional buckling mode shapes for the designated plates are plotted. The findings serve as valuable benchmark data for the thermal buckling analysis of FGM circular plates of variable thickness resting on elastic foundations.</p>