The construction industry is rapidly expanding, resulting in increased cement consumption and substantial environmental problems due to greenhouse gases. To mitigate this problem, it is critical to use sustainable and alternative building materials. Agricultural waste materials such as Rice Husk Ash (RHA) and Sugarcane Bagasse Ash (SCBA) are viable sources of supplementary cementitious materials because they are abundant, environmentally friendly, and exhibit pozzolanic properties. This study characterizes RHA and SCBA for use in concrete mixtures. The study conducts analyses of the chemical and physical properties of RHA and SCBA in order to determine their reactivity, compatibility with cement, and overall behavior in concrete mixtures. The study conducts an analysis of the chemical characterization (i.e., silica content, pH, carbonate content and iron content) and physical characterizations (i.e., specific gravity and fineness) of RHA and SCBA to determine the effect on concrete mixtures. In addition, the study conducted workability tests (slump test) of green concrete with 10% total cement replacement for 5% of each RHA and SCBA. The study findings indicate that both RHA and SCBA exhibit high levels of silica and are highly alkaline, suggesting both materials have excellent pozzolanic properties. The physical properties indicate that both RHA and SCBA have much lower densities and finer particle sizes that improve microstructure and particle packing. The workability of the concrete containing both RHA and SCBA showed a slump of 75 mm, indicating a medium level of workability, which is acceptable for practical use. Overall, the study findings indicate that RHA and SCBA are viable and sustainable substitutes for conventional cement materials and that the use of these two materials can help reduce the negative impacts of cement on the environment and improve resource conservation.