Foamed concrete (FC) is a lightweight, sustainable material with applications in construction, valued for its thermal insulation and acoustic properties. However, its reliance on Portland cement raises environmental concerns, while its porosity increases water absorption, limiting durability. This study addresses these challenges by incorporating recycled concrete aggregate (RCA) and rice husk ash (RHA) into FC formulations. RCA repurposes demolition waste but increases porosity, while RHA, a silica-rich by-product, enhances matrix densification through pozzolanic reactions. Existing research lacks insights into the combined effects of RCA and RHA on FC’s water and sound absorption properties. The study aims to optimize RCA and RHA proportions to enhance FC’s environmental and functional performance. Experiments involved preparing FC samples with varying RCA (10%–50%) and constant RHA (5%) proportions, followed by tests for water absorption and sound absorption coefficients. Results show RHA significantly reduces water absorption, with the lowest rate of 9.8% achieved at 10% RCA. Acoustic tests reveal that mid-to-high frequencies benefit from higher RCA-RHA mixes, while Mix 1 (10% RCA, 5% RHA) is ideal for applications requiring low water absorption and sound reflection, such as residential walls. In conclusion, the tailored use of RCA and RHA enhances FC’s durability and acoustic functionality, demonstrating a sustainable solution for eco-conscious construction. These findings contribute to advancing FC technologies by balancing eco-friendliness, performance, and material efficiency.