Solid waste management is one of the most serious issues confronting emerging countries like Ethiopia. Eggshells and corncobs were among that trash; rising population and urbanization have resulted in the development of many tons of solid garbage annually from diverse activities. Eggshell and corncob wastes can be reprocessed and utilized as a partial replacement for cement in mortar formulations. The purpose of this study was to investigate the durability and strength attributes of cement mortar using eggshell powder and corn cob ash as partial substitutes for ordinary Portland cement in regular mortar manufacture. Mortar mixtures were created by partially substituting cement with Eggshell powder and Corncob ash in various amounts (0%, 5%, 10%, 15%, 20%, 25%, and 30%) by weight, and the mixes were encoded using 2.5%,5%,7.5%,10%,12.5%,15%, and 20% by altering the ratio of eggshell powder and corncob ash. On mortar samples, tests for consistency, setting time, compressive strength, water absorption, sulphate attack, Ultrasonic Pulse Velocity, Fourier transform infrared (FTIR), Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA) were performed. The test findings suggested that the setting time of the mix increased with an increase in corncob ash content and vice versa with eggshell powder. The compressive strength of mortar rose with increasing eggshell powder share and dropped with increasing corncob ash, with findings recorded in the range of 27.27-20.28 MPa for the 28th-day sample with 5% and 30% Eggshell powder (ESP) and corncob ash (CCA), respectively. However, it rises as the curing days rise, whereas the mortar's water absorption rises as the replacement rises but falls as the curing days rise. Sample morphological structures improved as replacement and curing days increased. The loss of mass as the temperature rises increases with the replacement percentage. Also, Eggshell powder losses more weight when subjected to sulphate attack. From the result, 15% of 2:1 Eggshell powder (ESP) and Corncob ash (CCA) replacement produces mortar with optimal compressive strength. Keywords: Eggshell Powder, Corncob Ash, Mortar, Compressive strength, Sulphate attack, Water Absorption