Abstract The electronic, optical and thermoelectric properties of LaAlO₃ are studied under different pressure ranges (0–40 GPa) by using the full potential linear augmented plane wave method (FP-LAW). Calculations are done by Perdew–Burke–Ernzerhof generalized gradient approximation (PBEsol-GGA) by utilizing Wien 2k code. It was observed that with the increase of pressure band gap increased and the nature of band gap transform from indirect to direct. In Optical properties, optical conductivity, refractive index, absorption coefficient, and dielectric function are calculated at different pressures. Thermoelectric properties have been studied at temperature (150–800 K) and pressure (0–40 GPa) by using Boltz Trap code. At 800 K the values of power factor were 6.831 W K⁻². cm. s and 22.13 W K⁻². cm. s, respectively. Figure of merit was achieved up to 0.6. Results revealed that LaAlO₃ is a suitable candidate for optoelectronic and thermoelectric devices.