This study explores the application of a simplex lattice mixture design approach to optimize the utilization of diverse agricultural waste ash blends for enhancing the performance of concrete hollow blocks. The investigation examines the influence of varying the proportions of coconut husk ash, rice husk ash, and corn husk ash on the critical properties of the concrete hollow blocks, including water absorption, density, and compressive strength. The results demonstrate that the individual and interactive effects of the ash blends significantly impact the performance characteristics of the concrete hollow blocks. The optimal ash blend composition, which achieves a balance among the three critical performance metrics, was identified as 19.14% coconut husk ash, 15.44% rice husk ash, and 15.42% corn husk ash. The findings highlight the potential of agricultural waste ashes as sustainable and cost-effective supplementary cementitious materials for producing high-performance concrete hollow blocks. Further research is recommended to assess the long-term performance, environmental impact, and economic feasibility of these ash-blended concrete systems to promote their widespread adoption in the construction industry.