<p>Intensive poultry farming has significantly increased the incidence of lipid metabolic disorders, severely compromising the economic benefits of poultry industry. Currently, gamma-aminobutyric acid (GABA) is primarily used to mitigate adverse effects of heat stress in poultry, while the effects and mechanisms of GABA on lipid metabolism disorders remain underexplored. <i>Lactobacillus plantarum</i> (<i>L. plantarum</i>) serves as a significant source of GABA and is widely used in the livestock industry. This study therefore examines the effects of postbiotic GABA and the GABA-producing probiotic <i>L. plantarum</i> 1-2-3 on abdominal adipose tissue of laying hens following corticosterone-induced stress. To this end, hens subjected to corticosterone subcutaneous injections (4&#xa0;mg/kg of body weight) were respectively received GABA (100&#xa0;mg/kg BW) or <i>L. plantarum</i> 1-2-3 (1 × 10⁹ CFU/day). Results demonstrated that both GABA and <i>L. plantarum</i> 1-2-3 alleviated corticosterone-induced lipid metabolism disorders and reduced adipocyte size in abdominal fat. Additionally, expression analyses of genes and proteins related to lipid metabolism (PPARγ, C/EBPα, CD36, LPL, ATGL, and HSL) further showed that GABA and <i>L. plantarum</i> 1-2-3 inhibited excessive deposition of abdominal lipids in laying hens by suppressing adipogenesis and lipogenesis, while promoting lipolysis. Moreover, GABA and <i>L. plantarum</i> 1-2-3 both mitigated lipid deposition-induced inflammation and oxidative damage by normalizing macrophage infiltration and improving antioxidative enzyme activities (GSH-Px, T-SOD, CAT). These findings demonstrate the efficacy of GABA and <i>L. plantarum</i> 1-2-3 in alleviating lipid metabolism disorders in the abdominal adipose tissue of laying hens, suggesting their promise as nutritional supplements for counteracting stress-induced metabolic dysfunction.</p>