Tetrahydrocurcumin (THC), a curcumin derivative, shows potential in oncology and neurology. It regulates NF-κB, reduces inflammation, promotes cancer cell apoptosis, inhibits tumor angiogenesis, and enhances antioxidants, aiding in treating inflammation-related cancers. In neurology, THC’s anti-inflammatory and antioxidant properties protect neurons, reduce neuroinflammation, and support autophagy for cellular debris clearance, with its blood–brain barrier penetration offering a neuroprotective edge. Research on THC’s therapeutic application must focus on improving delivery and bioavailability and confirming its clinical safety and efficacy.