Using first-principles calculations, the fundamental understanding of the structure, electronic, elastic, lattice dynamic, and optic properties of three Mg-based ternary chalcopyrite semiconductors have been analyzed in detail within density functional theory scheme. To ensure an accurate determination of our calculated results, we considered five popular generalized gradient approximation formulations such as Perdew and Wang, Perdew–Burke and Ernzerhof (PBE), revised PBE, modified PBE, and Armiento–Mattson 2005 as well as local-density approximation (LDA) for the exchange-correlation potentials. It is found that all the calculated values of band gap for these compounds are underestimated compared to existing studies, while LDA-based functional gives better results than others. The electronic band structure demonstrated that these compounds have direct band gap at the Γ point in the Brillouin zone. It is observed that these compounds are mechanically stable in the chalcopyrite structure.