<p>The growing demand for multifunction compound that can withstand extreme environment has stimulated interest in refractory intermetallic silicide. In this study, a detailed investigation of the structural, mechanical, electronic, and optical properties of the transition metal silicide Hf₅Si₃ under pressure is carried out using density functional theory (DFT) within the framework of the generalized gradient approximation (GGA-PBEsol), as implemented in WIEN2k. Volume optimization along with negative formation energy and cohesive energy are examined that indicate structurally and thermodynamically stability of intermetallic compound Hf₅Si₃, respectively. Mechanical property analysis demonstrates high elastic moduli, mechanical anisotropy, covalent bonding and brittleness nature, with Poisson’s ratio (ν &lt; 0.26), Pugh’s ratio (B/G &lt; 1.75) and negative Cauchy pressure. Study of melting temperature shows high melting point (2230 ± 300K) at 15 GPa reflect thermal stability under extreme temperature. Debye temperature and elastic wave velocities increase with pressure reflects enhanced interatomic bonding strength, signifying a progressively stiffer and less compressible lattice. Optically Hf₅Si₃ exhibit strong absorption, high refractive index and large optical conductivity with optical anisotropy, highlighting potential for photonic and plasmonic study. Electronic band structure corresponding electron density of state confirm metallic nature of Hf₅Si₃. Finally, the charge density map analysis confirms the covalent bonding with a substantial metallic contribution of Hf₅Si₃. However, the comprehensive findings highlight the multifunctional nature of Hf₅Si₃ and its potential for diverse applications in extreme-environment structure, and optoelectronic.</p>