Cancer is the second leading cause of death worldwide, after cardiovascular diseases. Although chemoprevention targeting key signaling pathways has become an important strategy for reducing cancer risk, the clinical application of conventional anticancer drugs is limited by issues such as drug resistance, adverse effects, and poor responsiveness to immunotherapy. Natural plantderived compounds, characterized by low toxicity, multi-target effects, and potent biological activity, have gradually emerged as a new focus of anticancer research. In the present study, based on literature reviewed from databases such as PubMed, Web of Science, and CNKI, anticancer mechanisms of the marine carotenoid fucoxanthin were comprehensively and systematically elucidated. These mechanisms include the promotion of programmed cell death (apoptosis, autophagy, ferroptosis, and pyroptosis) through the induction of cancer cell cycle arrest,; regulation of pathways such as PI3K/AKT/mTOR and JAK2/STAT3/Bcl-xL; inhibition of angiogenesis and tumor metastasis via modulation of pathways such as Wnt/β-catenin and TGF-β; remodeling of the tumor immune microenvironment and gut microbiota, and systemic attenuation of the activation of key signaling pathways such as NF-κB and NLRP3 inflammasome pathways. These findings indicate that fucoxanthin may potentially serve as a pharmacotherapeutic agent with low toxicity and high antitumor activity.