Under nutrient-deficient conditions, plants reprogram their metabolic pathways to sustain growth and survival. GABA modulates nutrient uptake, carbon/nitrogen balance, and stress-related gene expression. It is rapidly synthesized via the decarboxylation of glutamate and accumulates in response to deficiencies in essential nutrients, such as nitrogen, phosphorus, and potassium. GABA not only serves as a carbon and nitrogen reservoir but also regulates ion transporters, maintains cellular pH homeostasis, and interacts with polyamines and proline to enhance stress resilience. Moreover, GABA influences root architecture, improves nutrient use efficiency, and supports energy production through its integration into the Tricarboxylic Acid (TCA) cycle via the GABA shunt. Recent findings highlight the role of GABA transporters and receptors in facilitating long-distance signaling under nutrient stress. This chapter discusses the biosynthesis, transport, and signaling mechanisms of GABA in plants during nutrient starvation, along with its interplay with metabolic and hormonal pathways. Understanding GABA’s multifaceted role provides insights into developing nutrient-efficient crops capable of withstanding harsh environmental conditions.