This study examines the potential of Controlled-Low Strength Material (CLSM) mixtures, enhanced with biochar, to serve as sustainable alternatives to conventional cement-treated base (CTB) for pavement base construction. The primary objective was to assess the influence of biochar on the flowability, compressive strength, and bleeding effects of CLSM mixtures, as well as to evaluate the environmental and economic impacts through a comprehensive life cycle assessment (LCA). The findings indicate that biochar incorporation significantly modified the flowability of CLSM, optimized compressive strength, and reduced bleeding rates. The desirable CLSM with biochar could achieve a balance between enhanced compressive strength and sustainability, demonstrating reduced greenhouse gas emissions and material costs in comparison to the traditional CTB mix. The research outcomes suggest that biochar-stabilized CLSM mixtures hold considerable promise as a more environmentally friendly and cost-effective alternative for pavement base construction. These innovative mixtures not only meet but also surpass the performance requirements traditionally fulfilled by CTB, marking a significant step toward sustainable infrastructure development.