Thermal utilization factors are crucial throughout the crop period, from seedling emergence to maturity, significantly affecting crop yield. Groundnut (ArachishypogaeaL.) shows drought tolerance through secondary metabolites, helping maintain biomass during arid conditions. This study compared heat use efficiency with the HR-LCMS profiling of phytochemicals in groundnut genotype GKVK-5. A field study was conductedon sandy loam soils at AHRS, Bavikere, UAHS, Shivamogga, Karnataka, India, under rain-fed circumstances during the (Kharif)season. Results showed GKVK-5 had a total dry matter of over 18.75g per plant, with an increased HUE of 14.56g ºC day⁻¹ at 90 days after sowing. Higher HTUE (2.258 q ha⁻¹ HTU⁻¹) resulted in more pod output (16.73 q ha⁻¹) and haulm yield (26.99 q ha⁻¹) compared to TMV 2 (10.48 q ha⁻¹ and 15.07 q ha⁻¹). The increase in HUE demonstrates GKVK-5’s tolerance to drought stress. During a qualitative phytochemical screening, GKVK-5’s leaf methanol extract tested positive for alkaloids, flavonoids, and phenolics. The quantitative estimation yielded values of 32.44μg/mg for total alkaloids, 38.61μg/mg for flavonoids, and 47.32μg/mg for phenolics.HR-LCMS profiling identified drought resistance-eliciting phytochemicals, such as 2-Amino-3-methylhexanoic acid, 6-Deoxyfagomine Maltoxazine, and 2-Furanyl pyrrolidine, in cation mode. Antioxidant flavonoids Astragalin 7-rhamnoside, Naringenin 7-O-glucoside, and PhenolicsRutin, Gallic acid, and quinic acid were detected in anion mode using high DB hits, retention duration, and MS spectra. These oxidative stress molecules led to enhanced heat use efficiency and drought stress adaptation in genotype GKVK-5.