The electronic and elastic properties of [Formula: see text] defect-chalcopyrite semiconductors have been studied using first-principle density functional theory (DFT) calculations. The lattice constants, energy band gap, elastic stiffness constants, bulk modulus, shear modulus, shear anisotropy factor, Young’s modulus, Debye temperature, Poisson’s ratio and B/G ratio have been computed. The values of elastic constants of 14 defect-chalcopyrites and Debye temperature for 18 compounds have been reported for the first time. The obtained results are in reasonable agreement with the experimental values in few cases where experiments are performed and reported values.