<p>In response to the challenge of brittle failure and the lack of nucleation sites in the EICP-solidified soil, a method for mechanical enhancement through the synergistic effect of xanthan gum (XG) and fibers was proposed. The mechanical properties, CaCO₃ content, water stability, and microstructural characteristics of EICP-solidified sand were systematically evaluated. Based on the experimental results, the enhancement mechanism of XG and fiber was then revealed accordingly. The results demonstrate that XG may enhance the immobilization of urease at contact points and provides nucleation sites for CaCO₃ precipitation, while fibers offer additional immobilization sites for urease and delay soil failure through a bridging effect. Under the CaCO₃-fiber-XG reinforcement system, the UCS of EICP-solidified sand was increased by up to 187.51%. Furthermore, the UCS, deformation modulus, and water stability of EICP-solidified sand exhibited a positive correlation with CaCO₃ content. As the CaCO₃ content increased from 1.5% to above 2.25%, the water stability of the EICP-solidified sand rapidly increased from 40% to approximately 90%. When the CaCO₃ content exceeded 2.25%, the water stability remained in the range of 90%-100%, showing excellent water stability.</p>