Background Soil salinization is a critical abiotic stressor that constrains crop production. By disrupting photosynthetic structures, inducing oxidative damage, and causing ion imbalance, it severely compromises the yield and quality of common bean (Phaseolus vulgaris L.). Gamma -Aminobutyric acid (GABA), a versatile non-protein amino acid, plays a pivotal role in regulating plant salt tolerance. However, whether GABA can effectively alleviate salt-induced damage in common bean, and the precise underlying regulatory mechanisms, remain to be fully elucidated. This study examines the effect of exogenous GABA on enhancing salt tolerance in common beans, laying the groundwork for breeding salt-tolerant varieties.Results Using the salt-sensitive common bean cultivar ‘Kaiman Brown’ as material, this study systematically elucidated the GABA-mediated salt tolerance regulatory network through integrated physiological-biochemical, transcriptomic, pan-targeting metabolomic, and WGCNA analyses. Results indicate that GABA significantly alleviates salt stress-induced inhibition of seedling growth by enhancing SOD, POD, and CAT activities, increasing osmotic regulator content, reducing MDA accumulation and electrolyte leakage, and improving photosynthetic systems. Additionally, GABA promotes synergistic oxygen-carboxylate metabolism via GABA shunting and 2-oxocarboxylic acid metabolism, thereby elevating citrate, aspartate, branched-chain amino acids, and proline levels. This reshapes osmotic homeostasis and carbon-nitrogen balance, laying a material foundation for subsequent stress responses. At the signal-regulation level, GABA effectively alleviates salt stress-induced inhibition of phospholipase PLIP1, thereby promoting its hydrolysis of ester bonds to generate lysophospholipids (LPL), thereby amplifying ABA signal intensity. By activating the PYR/PYL-PP2C-ABF core signaling module, it upregulates Perid genes to promote lignin synthesis, thereby fortifying cell walls and limiting Na⁺ influx. It also upregulates F3H genes to optimize flavonoid metabolism and increase rutin content, thereby enhancing the ROS scavenging capacity.Conclusion This study clarifies the physiological and molecular mechanisms by which exogenous GABA mitigates salt stress injury in commom bean, providing a theoretical basis and practical reference for the genetic omprovement and cultivation of salt-tolerant common bean varieties.