Abstract <p>Double perovskites (DPs) have garnered significant interest due to their promising applications in thermoelectric and optoelectronic technologies. In this study, we employ density functional theory (DFT) calculations to explore the structural, thermodynamic, mechanical and optoelectronic properties of the Na₂CsAgBr₆ DP compound under high-pressure conditions. Structural stability was assessed using the Perdew-Burke-Ernzerhof (PBE-GGA) potential, while optoelectronic properties were evaluated via the modified Becke-Johnson (mBJ) potential. The results reveals that the band gap decreases from 2.78 to1.65&#xa0;eV as the pressure increases from 0 to 30 GPa, respectively. The electronic density of states analyze indicates covalent bonding with reduced interatomic distances under compression. Mechanical stability was confirmed through the calculation of elastic constants, demonstrating that the compound retains its robustness across varying pressures. Optical analyze highlights absorption in the infrared region, reinforcing its potential for photonic applications. Furthermore, thermal stability was investigated using the Gibbs2 code within the WIEN2K package and VASP code, confirming the material resilience under extreme conditions. These findings provide crucial insights into the tunable nature of Na₂CsAgBr₆, offering a pathway for optimizing its properties for next-generation electronic and optical devices.</p> Graphical Abstract <p></p>