<p>Gastrointestinal cancers are among the top cancers worldwide. The interaction between gut microbiome and tumorigenesis of gastrointestinal tract has received much attention over the past decade. Gut dysbiosis is an emerging hallmark of gastrointestinal cancers, and it actively participates in the tumorigenesis by promoting tumor cell proliferation, production of detrimental metabolites, and deregulation of antitumor immune response. Accumulating evidence also infers the role of gut microbiome in modulating responses to chemotherapy and immunotherapy in gastrointestinal cancer. We are also beginning to witness attempts to translate microbiome-based strategies for gastrointestinal cancer diagnosis, prevention, and treatment. In this commentary, we highlight recent advances in our understanding of the role of gut microbiome in colorectal cancer, gastric cancer, and liver cancer, and discuss the translation of microbiome-based approaches to reduce the global burden of gastrointestinal cancers.</p>