Worldwide, garlic is one of the most important bulb vegetable crops and it has been cultivated from thousands of years ago due to its medicinal and nutritional benefits. The main goal of the current research was to explore the effect foliar application of γ-aminobutyric acid (GABA) on vegetative development and yield traits as well as chemical constitutes of garlic. To achieve this goal, two field experiments were performed during winter seasons of 2015/2016 and 2016/2017. Four concentrations of GABA (0, 1, 2 and 4 mM) were sprayed on two garlic's genotypes (Sids 40 and Egaseed). The results reported that exogenous supplementation of GABA notably improved vegetative growth (plant height and plant fresh weight), yield traits (bulb weight and total yield), and minerals content (N, P, K and Ca), as well as the content of organic compounds (total chlorophyll and total phenols) compared to non-treated plants (control) in both genotypes. It was clearly revealed that 1 mM GABA treatment had achieved the highest morphological traits, yield traits, chemical composition and organic compound content compared to the other GABA treatments. The findings indicate that GABA application has the ability to enhance growth and productivity of garlic through enhancing mineral composition and organic compounds.