Probiotics and postbiotics mechanisms of action and applications in early-onset colorectal cancer (EOCRC) prevention and treatment have significant importance but are a matter of debate and controversy. Therefore, in this review, we aimed to define the probiotics concept, advantages and limitations in comparison to postbiotics, and proposed mechanisms of anti-tumor action in EOCRC prevention and treatment of postbiotics. Biotics (probiotics, prebiotics, and postbiotics) could confer the health benefit by affecting the host gut microbiota directly and indirectly. The main mechanisms of action of probiotics in exerting anticancer features include immune system regulation, inhibition of cancer cell propagation, gut dysbiosis restoration, anticancer agents’ production, gut barrier function renovation, and cancer-promoting agents’ reduction. Postbiotics are suggested to have different mechanisms of action to restore eubiosis against EOCRC, including modulation of gut microbiota composition, gut microbial metabolites regulation, and intestinal barrier function improvement via different features such as immunomodulatory, anti-inflammatory, antioxidant, and anti-proliferative properties. A better understanding of postbiotics challenges and mechanism of action in therapeutic applications will allow us to sketch accurate trials in order to use postbiotics as bio-therapeutics in EOCRC.