In this study, we present our predicted results related to the structural, electronic, and optical properties of Ga(x)In(1-x)AsyN(1-y) quaternary alloys while assessing the associated zinc blende binary and ternary compounds. All calculations are performed by employing the full-potential linearized augmented plane wave plus local orbital method (FP-L(APW + lo)) based on density functional theory (DFT) and implemented in the WIEN2k computational package for crystalline materials. The exchange-correlation energy and potential functional are treated by the local density approximation (LDA) parameterized by Perdew-Wang (PW) and the PBE functional for solids, i.e., PBEsol-GGA, for the calculations of structural parameters, while the Tran-Blaha Becke-Johnson (TB-mBJ) potential approximation combined with PBE-GGA is applied for band structure calculation. The composition-dependent results of the lattice parameters, bulk modulus, and bandgap energy are also studied by performing a quadratic fit, where nonlinear variations in the results are observed. One can note that the bandgap energies are direct for all considered compositions (x, y). Moreover, the dielectric behavior, refractive index, and loss energy are predicted in the context of the optical properties, and the variation in the composition slightly affects the optical stability of the studied alloys. We have also carried out predictions of the thermodynamic properties such as the lattice parameter a(P, T), the Debye temperature theta(D), the heat capacity C-v, and the entropy S using the GIBBS program. To the best of our knowledge, this work represents the first theoretical study on these quaternary alloys and awaits experimental confirmation.