Abstract: Endoplasmic reticulum (ER), a multifunctional organelle in eukaryotic cells, is responsible for protein synthesis and intracellular signal transduction, which dominates cell function, survival, and apoptosis. Disequilibrium of ER homeostasis may induce ER stress, which closely intertwines with tumor occurrence and progress. A few clinical-used drugs (such as anthraquinones and oxaliplatin) can mediate the immunogenic cell death of tumor cells through excessive ER stress, and sequentially stimulate anti-tumor immune responses as well as long-term immune memory. However, these drugs often exhibit poor targeting ability and extremely low ER accumulation in tumor cells, limiting their clinical efficacy. Therefore, the researches of ER-targeted delivery of these drugs will significantly benefit the efficient and precise anti-tumor immunotherapy. In this review, we introduce the relationship between ER and tumor immunity, and summarize the ER targeting strategies for anti-tumor immunotherapy in recent years. Furthermore, we discuss the problems of existing ER targeting strategies and look into its broad prospects of application.