The introduction of glass matrix ceramics in dental restorations has revolutionized dental aesthetics. A key challenge in the development of dental glass ceramics is achieving nanocrystalline glass ceramics with superior mechanical properties without compromising translucency. In this study, ZrO₂–SiO₂ glass ceramics doped with amorphous Al₂O₃ were investigated to address these requirements. The results indicate that the segregation of Al³⁺ at the grain boundaries of ZrO₂ crystallites and the nano-domains of amorphous Al₂O₃ significantly influences the microstructure, including the grain size and stabilization of tetragonal ZrO₂, as well as the translucency and mechanical properties. The composition with 10 mol% Al₂O₃ exhibits the highest toughness of 8.05 MPa∙m^1/2 while maintaining excellent translucency. Moreover, the composition with 5 mol% Al₂O₃ demonstrates lower translucency but achieves a high flexural strength of 960 MPa. Overall, the mechanical properties of these translucent glass matrix ceramics surpass those of commercially available dental glass ceramics, highlighting their potential for dental restoration applications.