Lactic acid bacteria (LAB) have garnered significant attention for their potential role in mitigating cancer through various mechanisms of action, such as immunoregulation. The LAB, primarily from the genera Lactobacillus and Bifidobacterium, contribute to gut health by maintaining microbial balance, enhancing gut barrier function, and producing short-chain fatty acids (SCFAs). Colon cancer and colorectal cancer are some of the leading causes of cancer-related morbidity and mortality worldwide, with their incidence rising in many parts of the world. This review explores the ecology and the contributions of LAB species in maintaining the health of the human gut. We further discuss the specific mechanisms through which gut LAB may reduce the risk of colon cancer and/or colorectal cancer, including the modulation of inflammatory pathways, induction of apoptosis in cancer cells, regulation of gut microbiota composition, metabolic activity, and immunomodulation. By understanding these mechanisms, we could better appreciate the potential of LAB as a preventive strategy against cancer and inform future drug strategies and dietary recommendations.