Based on first principles computations, the structural, mechanical, electronic band structure, and optical properties of SeZnO3 compound have been predicted. The dependence of selected observables of SeZnO3 compound on the effective U (the Hubbard on-site Coulomb repulsion) parameter has been investigated in detail. The elastic constant, Young's modulus, bulk modulus, shear modulus, Poisson ratio, anisotropic factor, acoustic velocity, and Debye temperature have been computed. The calculated electronic band structure and density of states indicate that SeZnO3 is a semiconductor material and has indirect band gap. The computations of the optical spectra, as a function of the incident photon radiation in 0-35 eV energy range has also been performed and the interband transitions are examined. The results indicate that Hubbard parameter plays a crucial role in explaining mechanical, electronic, and optical properties of SeZnO3.