Immune checkpoint inhibitors (ICIs) enhance anti-tumor immunity, benefiting patients with dMMR/MSI-H tumors. Studies show ICIs, like pembrolizumab and nivolumab, improve outcomes in colorectal cancer, especially in dMMR/MSI-H cases. However, pMMR/MSS tumors are less responsive. Research focuses on combination therapies, including ICIs with chemotherapy, targeted drugs, and novel treatments, to improve efficacy in pMMR/MSS colorectal cancer. Biomarkers like TMB and POLE/POLD1 mutations predict ICI response, aiming to expand immunotherapy benefits.