Dihydroquercetin (DHQ), also known as taxifolin, is a naturally occurring flavonoid compound that serves as an active pharmaceutical ingredient. It is commercially available in the form of dietary supplements. As the reduced form of quercetin, DHQ contains five phenolic hydroxyl groups. This compound is capable of chelating transition metal ions, thereby effectively scavenging free radicals and detoxifying harmful substances while modulating enzyme activities. Consequently, DHQ exhibits potent antioxidant, anti-inflammatory, antiviral, and antibacterial properties. Given its significant pharmacological potential, DHQ exhibits anti-tumor activity against various malignant tumors, including breast cancer, gastric cancer, hepatocellular carcinoma, colonic neoplasms, melanoma, and prostate cancer. DHQ inhibits tumor occurrence and progression by regulating multiple signaling pathways, such as wnt/beta-catenin, phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), mammalian target of rapamycin (mTOR), transforming growth factor-beta (TGF-beta), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappa B), and mitogen-activated protein kinase (MAPK). The anti-tumor mechanisms of DHQ include inhibition of cell proliferation, invasion, and migration; induction of cell cycle arrest, activation of autophagy, apoptosis, epigenetic modification, suppression of epithelial-mesenchymal transition (EMT), enhancement of chemotherapy efficacy, and augmentation of immune function. In particular, DHQ potentiates the efficacy of chemotherapy drugs and augments immune function. Based on a systematic review of the pharmacological properties and anti-tumor mechanisms of DHQ across multiple malignant tumors, we conclude DHQ to be a promising natural compound with significant potential for anti-tumor therapy.