Purpose <p>This study investigates the buckling behavior of functionally graded carbon nanotube-reinforced composite (FG-CNT) plates subjected to linearly varying in-plane loads under thermal environments. The influences of CNT distribution patterns, boundary conditions, geometric parameters and temperature variations on the critical buckling load are examined.</p> Methods <p>The CNTs are assumed to be distributed through the plate thickness according to uniform distribution (UD) and two symmetric functionally graded distributions (FG-O and FG-X). The effective material properties are evaluated using the rule of mixtures. A Ritz formulation employing Chebyshev polynomial admissible functions is developed to determine the critical buckling loads. Various boundary conditions (CCCC, SSSS, SCSC, CSCF, CCFF and CFFF), aspect ratios, thickness-to-length ratios, temperature differences and non-dimensional load distribution coefficients are considered in the parametric analyses.</p> Results <p>The results reveal that the buckling response is significantly affected by the CNT distribution pattern, boundary conditions, thermal loading and geometric characteristics. Among the considered CNT distributions, FG-X generally provides the highest critical buckling loads, whereas FG-O yields the lowest values. Increasing temperature difference reduces the buckling resistance of the plates. The influence of the non-dimensional load distribution coefficient becomes more pronounced depending on the plate geometry and support conditions.</p> Conclusions <p>The proposed Chebyshev-Ritz formulation accurately predicts the buckling response of FG-CNT reinforced composite plates subjected to linearly varying in-plane loads in thermal environments. The presented results provide useful design guidelines for the analysis and optimization of advanced CNT-reinforced structural components operating under non-uniform mechanical and thermal loading conditions.</p>