The study investigates the role of iRhomi (a protein with homology to rhomboid intramembrane proteases) in cancer chemotherapy resistance and immune response. iRhomi is found to negatively regulate chemotherapy sensitivity by modulating the MAPK14-HSP27 axis and inhibiting the cytotoxic T-cell response by reducing ERAP1 protein stability and antigen processing. To overcome these challenges, a biodegradable nanocarrier (PCL-CP) is developed to co-deliver iRhomi pre-siRNA and chemotherapeutic drugs. This nanocarrier effectively targets and penetrates tumors through enhanced permeability and retention (EPR) and CD44-mediated transcytosis. Inhibition of iRhomi further enhances tumor targeting and uptake, leading to improved antitumor efficacy and activation of the tumor immune microenvironment in multiple cancer models in female mice. The combination of iRhomi inhibition with chemotherapy represents a promising strategy to overcome chemio-immune resistance in cancer treatment.The study investigates the role of iRhomi (a protein with homology to rhomboid intramembrane proteases) in cancer chemotherapy resistance and immune response. iRhomi is found to negatively regulate chemotherapy sensitivity by modulating the MAPK14-HSP27 axis and inhibiting the cytotoxic T-cell response by reducing ERAP1 protein stability and antigen processing. To overcome these challenges, a biodegradable nanocarrier (PCL-CP) is developed to co-deliver iRhomi pre-siRNA and chemotherapeutic drugs. This nanocarrier effectively targets and penetrates tumors through enhanced permeability and retention (EPR) and CD44-mediated transcytosis. Inhibition of iRhomi further enhances tumor targeting and uptake, leading to improved antitumor efficacy and activation of the tumor immune microenvironment in multiple cancer models in female mice. The combination of iRhomi inhibition with chemotherapy represents a promising strategy to overcome chemio-immune resistance in cancer treatment.