<p>The rapid growth of the construction industry drives high cement production, depleting natural resources, increasing costs, and releasing harmful pollutants like carbon dioxide (CO₂) into the atmosphere. Additionally, the disposal of waste by-products in landfills harms the environment. To address these issues, this research investigates using pozzolanic waste materials, such as palm oil fuel ash (POFA) and sugarcane bagasse ash (SCBA), as partial cement replacements in mortar. The study evaluates the performance of mortar with 0–20% POFA and SCBA, assessing the materials' physical, chemical, and morphological properties, as well as the fresh, hardened, and durable performance, including workability, compressive strength, modulus of elasticity, water absorption, and acid resistance. A life-cycle assessment (LCA) was also conducted to analyze CO₂ emissions and overall costs. The results showed a consistent decrease in workability, compressive strength, and modulus of elasticity with POFA and SCBA compared to the control mix. However, Mix G (15% POFA and 5% SCBA) improved workability, compressive strength, and modulus of elasticity by 3.97%, 29.12%, and 10.41%, respectively, compared to the control mix. Water absorption and mass loss also decreased by 3.81% and 28.38%, respectively. Besides, eco-strength efficiency analysis revealed a 17.84% reduction in CO₂ emissions and a 16.27% reduction in production costs per cubic meter for a mix with 20% POFA and SCBA. The study concludes that an optimal combination of POFA and SCBA enhances mortar's strength and durability, with higher POFA content potentially reducing performance, underscoring their potential as sustainable and cost-effective concrete materials.</p>