In light of increasing environmental and health risks from gold mining tailings, this study investigates the use of detoxified tailings from PT Agincourt Resources in concrete block production via solidification/stabilization. Portland cement was blended with subsoil and tailings at varying ratios, and blocks were evaluated for compressive strength, water absorption, and leaching behavior (TCLP). The optimal cement–tailings mixture (1:1) attained 102.33 kg/cm² (Grade I), while the cement–subsoil–tailings blend (7:3) reached 68.32 kg/cm² (Grade II); both met durability and environmental safety criteria. These results demonstrate a novel circular‐economy strategy that repurposes mining waste into structurally robust, eco‐friendly construction materials. The approach offers potential for reducing cement consumption and heavy‐metal leaching. Further research should explore long‐term performance and industrial scalability to maximize environmental and economic benefits globally.