Key message <p>AtGASA1 regulates plant growth and development, while conserved Cys-40 and Cys-44 residues in its GASA domain are crucial for controlling ROS accumulation under salt stress.</p> Abstract <p>AtGASA1 is a member of the gibberellin acid-stimulating protein (GASA) family, characterized by a GASA domain containing 12 conserved cysteine-rich peptides (CRP). Members of the GASA family are known to play an essential role in plant responses to both biotic and abiotic stresses; however, the function of AtGASA1 remains unclear. In this study, we found that <i>gasa1</i> mutants exhibited sensitivity to salt stress, accompanied by increased accumulation of reactive oxygen species (ROS). In contrast, <i>AtGASA1</i>-overexpressing plants exhibited enhanced salt tolerance and significantly reduced ROS levels. These findings indicate that <i>AtGASA1</i> positively regulates salt stress tolerance, likely through modulating ROS homeostasis. To explore the role of conserved cysteine residues within the GASA domain, site-directed mutagenesis was performed to substitute Cys-40 and Cys-44 with alanine. Functional assays in a yeast heterologous expression system showed that yeast expressing AtGASA1^C40,44A displayed reduced tolerance to salt stress compared with yeast expressing non-mutated AtGASA1, indicating that these residues are critical for salt stress adaptation. Consistently, transgenic <i>Arabidopsis</i> plants overexpressing AtGASA1^C40,44A accumulated higher levels of ROS compared with <i>35S::GASA1</i> plants. Collectively, our findings demonstrate <i>AtGASA1</i> may contribute to enhanced salt tolerance in <i>Arabidopsis</i>, potentially through modulating ROS accumulation.</p>