This study pioneers the synergistic application of polyaspartic acid (PAsp) and poly-lysine (PLys) as dual polypeptide additives to enhance microbially induced calcium carbonate precipitation (MICP) for sand consolidation. Capitalizing on their complementary charge properties-anionic PAsp chelates Ca2+ ions while cationic PLys bridges microbial cells to sand grains-this novel formulation significantly optimizes biocementation efficiency. For practical implementation, limestone waste-derived calcium acetate reduced material costs by 32 % versus conventional calcium chloride. At the optimal 5:5 PAsp:PLys ratio (100 mg/L total concentration), MICP-treated samples exhibited exceptional performance improvements: 212.50 % increase in unconfined compressive strength, 68.43 % higher CaCO3 content, 57.28 % reduction in permeability, and the dry density enhanced by 25.65 % compared to the samples without polypeptide with only 3 % additional treatment cost. ESEM/XRD analysis revealed vaterite-dominated crystallization with tunable morphology via polypeptide ratio adjustment. This cost-effective strategy demonstrates high potential for field implementation in desertification control and geotechnical reinforcement of erosion-prone slopes, embankments, and roadbeds.