Lifestyle, diet, and genetics are established risk factors for developing colorectal cancer (CRC). In recent years, the role of the gut microbiota (GM) has been increasingly highlighted in several studies, suggesting an effect on both the disease's pathogenesis and the efficacy and tolerability of treatments. We conducted a search on Medline, aiming to identify published studies exploring the role of the GM in the development and treatment of CRC. Dysbiosis, an imbalance in GM, is common in CRC patients and is associated with precancerous lesions, aggressive tumors, and varied therapy outcomes. Restoring GM balance can reduce treatment complications and may improve prognosis. The review details how GM influences CRC through metabolite production, inflammation modulation, and immune response alteration. Diet significantly impacts GM composition, with processed meats and high-fat diets increasing CRC risk, while fiber-rich diets are protective. The role of the GM in CRC treatments like surgery, chemotherapy, radiotherapy, and immunotherapy is also explored, noting its influence on complications, chemoresistance, and treatment efficacy. Future strategies involving GM modulation through diet, probiotics, and fecal microbiota transplantation (FMT) show promise for CRC prevention and treatment, warranting further research.