<p>Magnesium–Aluminum–Zinc (Mg–Al–Zn) alloys are widely utilized in industry, with AZ91D alloy being a benchmark due to its high strength, corrosion resistance, and castability. However, its use in thixomolding, a semi-solid manufacturing process ideal for precision components, remains constrained by poor ductility and thermal conductivity, which are critical for automotive and electronics applications. In this study, a series of Mg–Al–Zn alloys with fixed total Al + Zn content (10 wt pct) but varying Al/Zn ratios was systematically investigated to establish composition–microstructure–property relationships. The results show that increasing Al promotes higher yield and tensile strength through Mg₁₇Al₁₂ precipitation, but reduces ductility and thermal conductivity. Conversely, Zn additions enhance ductility and thermal conductivity by promoting solute strengthening and reducing intermetallic connectivity. Alloys with intermediate Al/Zn ratios (<i>e.g.</i>, AZ64 to AZ37) achieve a balanced performance, with ultimate tensile strength above 294&#xa0;MPa, elongation exceeding 12 pct, and thermal conductivity in the range of 58 to 73 W/(m·K). These findings provide critical guidance for tailoring Mg alloys optimized for thixomolding, offering pathways toward lightweight structural and thermal management components in automotive and electronics applications.</p>