GABA is a nonprotein amino acid composed of a four-carbon backbone, which serves as a multifunctional signaling compound across diverse organisms, including both animals and plants. In plants, GABA plays an integral role in regulating a wide range of physiological and molecular processes. These include maintaining redox balance, stabilizing cytosolic pH, adjusting osmotic potential, and facilitating nitrate absorption and assimilation. It is also involved in carbon and nitrogen metabolism, directing pollen tube navigation, modifying cell walls, supporting adventitious root formation, and influencing plastid-related activities. In addition to its contributions to general plant growth and development, GABA is recognized for its role in enhancing tolerance to both biotic and abiotic stresses. It also has significant functions in regulating leaf senescence and maturation, as well as improving the quality and longevity of postharvest produce. Advancing our understanding of GABA’s multifaceted roles is essential for optimizing plant performance across a range of environmental conditions, including both normal and stress-induced scenarios.