Dying tumor cells release biological signals that exhibit antigenicity, activate cytotoxic T lymphocytes, and induce immunogenic cell death (ICD), playing a key role in immune surveillance. We demonstrate that the flavonoid LW-213 activates endoplasmic reticulum stress (ERS) in different tumor cells and that the lysosomal calcium channel TRPML1 mediates the ERS process in human cellular lymphoma Hut-102 cells. Apoptotic tumor cells induced by ERS often possess immunogenicity. Tumor cells treated with LW-213 exhibit damage-associated molecular patterns (DAMPs), including calreticulin translocation to the plasma membrane and extracellular release of ATP and HMGB1. When co-cultured with antigen-presenting cells (APCs), LW-213-treated tumor cells activated APCs. Two groups of C57BL/6J mice were inoculated with Lewis cells: a “vaccine group”, which demonstrated that LW-213-treated tumor cells promote the maturation of dendritic cells and increase CD8 T cells infiltration in the tumor microenvironment and a “pharmacodynamic group”, treated with a combination of LW-213 and PD1/PD-L1 inhibitor (BMS-1), which reduced tumor growth and significantly prolonged the survival time of mice in the “pharmacodynamic group”. Therefore, LW-213 can be developed as a novel ICD inducer, providing a new concept for antitumor immunotherapy.Copyright © 2023. Published by Elsevier B.V.