ERp29 is an endoplasmic reticulum (ER) stress-inducible protein. It was found that ERp29 was highly expressed in several cancers and associated with resistance to oxidative and radiation stress, which may serve as a novel target for nasopharyngeal carcinoma (NPC) anticancer approach. In this study, we used immunohistochemistry to detect ERp29 expression in radioresistant and radiosensitive NPC tissues. As a result, ERp29 was up-regulated in radioresistant NPC tissues compared to radiosensitive NPC tissues. We also found that ERp29 knockdown attenuated radioresistance of NPC CNE-1 cells and ERp29 overexpression enhanced radioresistance of NPC CNE-2 cells. When exposed to radiation, ERp29 knockdown CNE-1 cells increased radiation-induced cell apoptosis and ERp29 overexpression CNE-2 cells reduced radiation-induced cell apoptosis. Further, we demonstrated that ERp29 up-regulated the expression of Hsp27. In conclusion, our study supports ERp29 could potentiate resistance to radiation in NPC cells, targeting of ERp29 is a rational strategy in treating radioresistant NPC.