ER stress activates the unfolded protein response (UPR), a critical mechanism for maintaining cellular homeostasis in plants. The p24 protein family is known to be involved in protein trafficking between the endoplasmic reticulum (ER) and the Golgi apparatus, but its role in ER stress remains unclear in plants. In this study, we found that Atp24δ8(delta8), a member of the δ-2 subclass of the p24 family, is significantly upregulated in response to tunicamycin-induced ER stress. Subcellular localization confirmed that Atp24δ8 resides in the ER, and CRISPR-Cas9 loss-of-function mutants displayed increased sensitivity to ER stress. Further analysis showed that Atp24δ8 regulates key UPR genes, highlighting its role in promoting ER stress tolerance. These findings provide new insights into the molecular mechanisms that plants use to cope with ER stress, potentially contributing to the development of stress-tolerant crops.