Utilizing waste materials in construction is a creative way to promote sustainability as the need for building materials continues to rise due to infrastructure growth. Cement is a commonly used material globally, and contributes to environmental problems solving through the use of nonrenewable resources and CO2 emissions. Using waste materials as a partial or full replacement, such as eggshell ash and granite waste powder can be reprocessed and utilized as a partial replacement for cement in mortar production. This study aimed to investigate the effect of partial replacement of cement with eggshell ash and granite waste powder in cement mortar at 0, 5, 10, 15, 20, 25, and 30% by weight of cement as per ASTM C109. To accomplish the objective of this finding a detailed experimental analysis was performed to evaluate the fresh, hardening, and microstructural properties of mortar. The workability of fresh mortar, compressive strength, bulk density, water absorption, porosity test, ultrasonic pulse velocity, and sulfate attack, tests are conducted for different curing ages (3, 7, 28, 56, and 91) days. The result of BET demonstrates that eggshell ash and granite waste powder are very fine materials. Also, the chemical properties of ESAGWP meet the relevant ASTM C618 standard. The finding of the research indicates that using ESAGWP at 15% replacement gives the maximum compressive strength, bulk density, and UPV have all been enhanced, particularly in the later age of mortars. However, when using 20%, 25%, or 30% replacement, there's a small decrease in strength compared to the control mix. The workability of the mortar also decreases as the replacement percentage increases because ESA&GWP has a high surface area and requires high water demand. Furthermore, the samples showed a reduction in porosity, and water absorption capacity as the replacement percentage increased up to ESA&GWP 15% replacement after 15% replacement there is a slight increment of porosity and water absorption. The microstructure of the finding reveals that the 15% replacement of the ESAGWP mix is particularly dense and structural compactness. Thus, the study recommended that the utilization of eggshell ash and granite waste powder (ESAGWP) as a supplementary cementitious material in mortar production should be encouraged. Keywords: Durability, Eggshell Ash, Fresh Mortar Properties, Granite Waste Powder, Mechanical Properties, Microstructure