Colorectal cancer (CRC) is a growing concern worldwide, particularly affecting younger populations in recent years. The progression of CRC involves diverse molecular pathways, each contributing to how the tumor behaves and responds to treatment. The immune system is crucial in detecting and destroying cancer cells, but tumors can avoid immune destruction through various strategies, such as altering antigen expression or reshaping their environment to suppress immune activity. These escape mechanisms have prompted the development of immunotherapy, which has significantly improved outcomes for patients with specific genetic profiles like microsatellite instability-high (MSI-H) or mismatch repair deficiency (dMMR). Drugs such as pembrolizumab, nivolumab, and others have demonstrated notable clinical benefits in these populations. Research is now expanding to evaluate immunotherapy in earlier stages of disease and in combination with other treatments like chemoradiation, even in patients without traditional predictive biomarkers. Ongoing studies are also exploring novel immune targets and combinations to enhance effectiveness and broaden access to these therapies. Understanding the interaction between tumor biology and the immune system is essential for advancing personalized care in CRC.