Metal and metalloid stress pose a significant threat to plant growth, development, and productivity. Among various plant defense strategies, gamma-aminobutyric acid (GABA) has gained attention for its crucial role in mitigating metal-induced toxicity. This chapter explores the protective functions of GABA under heavy metal and metalloid stress. GABA enhances stress tolerance by modulating key metabolic enzymes (GABA transaminase (GABA-T) and succinate semialdehyde dehydrogenase (SSADH)), strengthening antioxidant defense systems (superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), ascorbate, glutathione), and regulating gene expression within the GABA shunt. Furthermore, GABA acts as a signaling molecule, activating downstream pathways that alleviate oxidative damage, restrict metal uptake, and promote plant growth under stress conditions. It also contributes to cellular redox homeostasis and ion balance, reinforcing overall plant resilience. The chapter highlights recent research advances and discusses the potential of GABA-based strategies in phytoremediation and sustainable agriculture, offering valuable insights into improving plant performance in metal-stressed environments.