Concrete is the most commonly used material in the world for construction, and to produce this large amount of concrete requires the production of large quantities of cement, which results in the degradation of the environment by releasing harmful gases. One approach for making eco-friendly concrete is to use less cement in concrete; for that aim, other cementitious materials can be utilized as a partial replacement for cement. This study focuses on the mechanical and durability properties of concrete having limestone powder (LSP) as a partial replacement for cement. Five different combinations are considered for this study; the LSP replacement level is 5, 10, 15, and 20% (by weight). The result indicates that the slump value increases with increasing LSP content. At 28 days, compressive strength and flexural strength are the highest for replacing 10% cement with LSP. The concrete cylinders are subjected to elevated temperatures (200 and 400 °C) for one hour and then cooled down to room temperature (25 °C). Reduction in compressive strength with increased temperature is up to 6% at 200 °C temperature and up to 11% at 400 °C temperature. Therefore, incorporating 10% LSP in concrete as a replacement for Portland cement will increase concrete's mechanical and durability properties.