Colorectal cancer is one of the top contributors to the global burden of cancer incidence and mortality with genetic and environmental factors contributing to its etiology. Modifiable or environmental factors can be the cause of up to 60% of the risk of developing colorectal cancer. Hence, there is a growing interest in specifically defining what can be improved in our lifestyle to reduce this risk, improve the effectiveness of treatments, reduce side effects, and decrease the risk of recurrence. One of the elements directly related to lifestyle is gut microbiota. The microbial ecosystem has a vital role in colorectal cancer prevention and antitumoral response through modulation of the immune system and production of short-chain fatty acids. Numerous approaches have been used to identify healthy microbiota that can reduce the risk of cancer development, improve treatment efficacy, and reduce side effects. Scientific literature in this subject is growing exponentially and, therefore, systematic reviews and meta-analysis are required to ensure that appropriate recommendations are given to patients. This work aimed to perform a systematic analysis of the published literature to elucidate whether microbiota modulation through pre-, pro-, symbiotic treatment and/or nutritional intervention can be beneficial for patients diagnosed with colorectal cancer. Detailed analysis of published studies shows that some prebiotics, such as inulin and resistant starch, probiotics such as lactic strains producers of short-chain fatty acids, and consumption of unprocessed plant products, can be effective recommendations for patients diagnosed with colorectal cancer. This advice should always be individually tailored and followed up by a healthcare professional with expertise in the field.