The Nuclear Waste Repository requires rock types with excellent thermomechanical stability. Therefore, a comprehensive understanding of rock behaviour is crucial in selecting a suitable host rock. To assess the viability of two different kinds of Jalore granitoid rocks (golden and white granites) for this purpose, the focus of this study is on examining damage characteristics during the selection process. The study involved subjecting rock specimens to thermal cycles below the damage threshold temperature (250 °C). The experimental setup involved subjecting rock specimens to nine thermal cycles of heating up to 250 °C for 12 h, with constant heating and cooling rates. Stress–strain characteristics under tension (Brazilian disc test) were recorded for the Jalore granitoid rocks at different thermal cycles. Based on Lemaitre’s strain equivalent principle, along with statistics and damage theory, a model for thermal cycle-induced damage under indirect tension was established. Additionally, surface morphology (SEM) analyses were conducted on the thermally treated rocks. Thermogravimetric analysis (TGA) and differential thermal analysis (DT) were used to identify changes in thermal and kinetic behaviours. The results indicate that as the number of thermal cycles increases, the strains accumulate, and the elastic wave velocity and rock strength decrease. Thermal damage in the form of mass loss and reduction in elastic wave velocity is attributed to thermal cracks and nonuniform grain expansion along the grain boundaries on the rock surface. Tensile strength and elastic modulus decrease with an increase in thermal cycles. Granitic rocks exhibit noticeable damage below three thermal cycles. However, after undergoing three cycles, the rate of change in damage becomes minimal and consistent across both types of granitic rocks.