This study evaluated the effects of 5, 10, and 15 mM γ-aminobutyric acid (GABA) on the postharvest quality and antioxidant system of strawberries. The application of GABA did not affect fruit skin color and firmness but significantly reduced weight loss, particularly at 10 mM. GABA treatments increased total soluble sugar, titratable acid, SOD, and CAT activities, with 10 mM being the most effective. Specifically, 10 mM GABA significantly induced the accumulation of fructose, oxalic acid, and succinic acid. Additionally, GABA increased total anthocyanins, total flavonoids, and DPPH radical scavenging activity, while reducing ROS and MDA content. These findings suggest that 10 mM GABA is a promising strategy to improve the postharvest marketability of strawberries by maintaining fruit quality and enhancing the antioxidant system.This study evaluated the effects of 5, 10, and 15 mM γ-aminobutyric acid (GABA) on the postharvest quality and antioxidant system of strawberries. The application of GABA did not affect fruit skin color and firmness but significantly reduced weight loss, particularly at 10 mM. GABA treatments increased total soluble sugar, titratable acid, SOD, and CAT activities, with 10 mM being the most effective. Specifically, 10 mM GABA significantly induced the accumulation of fructose, oxalic acid, and succinic acid. Additionally, GABA increased total anthocyanins, total flavonoids, and DPPH radical scavenging activity, while reducing ROS and MDA content. These findings suggest that 10 mM GABA is a promising strategy to improve the postharvest marketability of strawberries by maintaining fruit quality and enhancing the antioxidant system.