<p>Within a decade, MAX phase borides have drawn interest in research owing to their enhanced thermal and mechanical properties. In this work, we present a comprehensive study of the stability and structural, electronic, mechanical, and optical properties of Y₂AB (A = Ga, In) boride MAX phases. The density functional theory (DFT) is used to investigate and analyze the properties of these compounds. Chemical stability is predicted by calculating the formation energy, while mechanical stability is confirmed through the stiffness constant <i>C</i>_<i>ij</i>. The electronic band structure confirms the material’s metallic nature and anisotropic behavior, while the density of states (DOS) reveals the covalent chemical bonding within the compounds. To understand the mechanical behavior of this compound, elastic moduli, bulk modulus, shear modulus, and Vickers hardness have been investigated. According to Poisson’s ratio and Pugh’s ratio, Y₂AB (A = Ga, In) are predicted as a ductile material. In addition, optical properties such as reflectivity (<i>R</i>), refractive index (<i>n</i>), absorption coefficient (<i>α</i>), extinction coefficient (<i>k</i>), photoconductivity (<i>σ</i>), and loss function (LF) have been studied for possible applications of the compounds to optical systems. These findings indicate that Y₂GaB and Y₂InB have potential use in UV-protective coatings, sensors, photodetectors, medical sterilization systems, and optical coating applications.</p>