Heat stress is a major abiotic factor limiting soybean productivity, particularly in tropical regions experiencing rising temperatures. This study aimed to identify heat-tolerant soybean genotypes by integrating morphological and physiological analyses. Eighteen varieties were evaluated under five temperature regimes (T₀ to T₄: 25, 30, 35, 40, and 45°C) in a factorial completely randomized design with three replications. Eleven morpho-physiological traits were assessed, including survival rate, meristem node count, root and shoot length, total plant biomass, root-to-shoot ratio, relative water content, leaf area, SPAD, membrane stability index (MSI), and heat tolerance index (HTI). Data were analyzed using ANOVA, Tukey's HSD, correlation matrices (genotypic, phenotypic, environmental), and principal component analysis (PCA). Biplots and heatmaps were used to visualize trait associations and varietal clustering. Significant genotype × treatment interactions (p < 0> 0.80), whereas MSI showed consistent negative correlations with growth traits (r < –0.70), identifying it as a key stress marker. Environmental correlations were weak, suggesting a predominantly genetic basis for variation. PCA explained 81.2% of variance through the first two components under 45°C, clearly separating tolerant (V₁₆, V₁₇, V₃) from sensitive (V₁₃, V₁₈) genotypes. These findings validate the integrated phenotyping approach for screening thermotolerance. V₁₆ and V₁₇ are especially promising for future breeding programs aimed at developing heat-resilient soybean cultivars.