The study evaluates the impact of barite and hydraulic lime on the physical and mechanical properties of mortars exposed to high temperatures. Six mortar formulations were developed, incorporating a volumetric substitution of 0% or 33% of cement with hydraulic lime, and 0%, 50%, or 100% of sand with barite, these formulations conduct to obtain more eco-friendly mixtures than conventional cement-based concrete. The physical properties (density, ultrasonic pulse velocity, water absorption by immersion and capillarity) and mechanical properties (dynamic modulus of elasticity, compressive strength, and tensile strength) were measured after exposure to 20 °C, 300 °C, and 600 °C. A surface and microscopic morphological analysis of the samples, using scanning electron microscopy (SEM), was also conducted. The results indicate that the addition of barite increases the density and water absorption of the mortars. Barite improves the tensile strength while decreasing the dynamic modulus of elasticity at high temperatures. At 300 °C, the incorporation of barite and hydraulic lime increases compressive strength, while a significant decrease is observed at 20 °C and 600 °C. Compressive strength remains stable for reference mortars and those with 50% barite but decreases with 100% barite and in the presence of lime. Furthermore, the combined use of barite and hydraulic lime visibly improves the morphology of the mortars after exposure to elevated temperatures. These results demonstrate that barite and hydraulic lime can enhance the resilience of mortars subjected to thermal stress, thus contributing to more durable and high-performing construction materials.