Gastrointestinal cancer (GIC), including gastric cancer and colorectal cancer, is a common malignant tumor originating from gastrointestinal epithelial cells. Although the pathogenesis of GIC remains unclear, aberrant lipid metabolism has emerged as a hallmark of cancer. Several enzymes, proteins, and transcription factors are involved in lipid metabolism reprogramming in GIC, and their abnormal expression can promote lipid synthesis and accumulation of lipid droplets through numerous mechanisms, thereby affecting the growth, proliferation, and metastasis of GIC cells. Studies show that some natural compounds, including flavonoids, alkaloids, and saponins, can inhibit the de novo synthesis of lipids in GIC, reduce the level of lipid accumulation, and subsequently, inhibit the occurrence and development of GIC by regulating Sterol regulatory element-binding protein 1 (SREBP-1), adenosine monophosphate-activated protein kinase (AMPK), 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), phosphatidylinositol-3-kinase/Akt and the mammalian target of rapamycin PI3K/Akt/mTOR, amongst other targets and pathways. Therefore, targeting tumor lipid metabolism is the focus of anti-gastrointestinal tumor therapy. Although most natural products require further high-quality studies to firmly establish their clinical efficacy, we review the potential of natural products in the treatment of GIC and summarize the application prospect of lipid metabolism as a new target for the treatment of GIC, hoping to provide a reference for drug development for gastrointestinal tumors.