Background: Prolyl 4-hydroxylase, beta polypeptide (P4HB) and Glucose‑regulated protein 78 (GRP78) represent for poor prognosis of various cancers, while rare research investigate correlation of them. This study aimed to explore the correlation and prognostic value of P4HB and GRP78 expression combined with clinical features in gastric cancer (GC).Methods: 150 GC tissue samples evaluated P4HB and GRP78 protein expression by immunohistochemistry separately. Association of the expression with clinicopathological features was analyzed. To explore correlation between their mRNAs and pathways, bioinformatics analyses were performed. Kaplan-Meier analyses were taken to compare survival curves. Univariate and multivariate Cox regression models were used to analyze potential prognostic factors of overall survival (OS). Basing on the multivariate Cox regression model, a prognostic nomogram was constructed, discrimination ability and clinical usefulness of which were compared to TNM stageResults: P4HB and GRP78 expression were both associated with tumor invasion and lymph node metastasis. P4HB protein positive correlated with GRP78, as the same tendency of mRNAs in both GC tissue and cell databases. Bioinformatics analyses indicated that P4HB and GRP78 may be associated with protein folding and response to ER stress, as well as with the protein processing in ER pathway. High single expression or co-expression of P4HB and GRP78 indicated a shorter OS. When stratified by postoperative adjuvant chemotherapy, high co-expression was only represented for unfavorable prognosis in the group with chemotherapy, especially in advanced stage. Multivariate Cox regression analysis identified differentiation (P = 0.020, HR = 1.846, 95% CI: 1.099-3.101), TNM stage (P < 0.001, HR = 3.124, 95% CI: 1.870-5.217), postoperative adjuvant chemotherapy (P = 0.005, HR = 0.507, 95% CI: 0.317-0.810) and P4HB and GRP78 co-expression (P = 0.002, HR = 2.304, 95% CI: 1.355-3.915) were independent prognostic factors for OS. The nomogram was better than TNM stage in discrimination ability and clinical usefulness from the receiver operating characteristic (ROC) and decision curve analysis (DCA) curves.Conclusion: P4HB may positive correlate with GRP78 expression in GC. Co-expression of them can be an independent prognostic factor, serving as a predictive biomarker for GC patients, especially for advanced stage with postoperative adjuvant chemotherapy. And the nomogram may be better than TNM stage in discrimination ability and clinical usefulness.