<p>Amorphous microwires (AMWs) are well known for their high strength and elastic limit, making them excellent candidates for various engineering applications. However, one of the key challenges in utilizing AMWs is their inherent variability in mechanical performance, particularly in achieving stable fracture strength across different compositions. This study provides critical insights into the relationship between microstructure and mechanical behavior by investigating CuZr-based AMWs with varying compositions during quasi-static tensile fracture. Specifically, uniaxial tensile tests on Cu₄₈Zr₄₈Al₄, Cu₄₅Zr₄₅Co₁₀, and Cu₄₈Zr_47.2Al₄Nb_0.8 AMWs, combined with log-normal and Weibull statistical analysis, revealed that Cu₄₈Zr_47.2Al₄Nb_0.8 exhibits the highest fracture reliability (<i>m</i>_Tr = 3.97) and fracture threshold (<i>σ</i>_μTr = 1307&#xa0;MPa), while Cu₄₈Zr₄₈Al₄ showed the lowest performance (<i>m</i>_Tr = 3.08,<i> σ</i>_μTr = 1085&#xa0;MPa). Moreover, a standard power-law relationship exists between the characteristic size <i>L</i> of the fracture surface and the degree of order <i>O</i> was established, linking atomic mixing enthalpy and atomic radius to structural homogeneity and fracture behavior. This study provides an important perspective for optimizing AMW compositions to achieve higher fracture strength and improve the reliability for engineering applications.</p> Graphical Abstract <p></p>