Theaflavins (TFs) is natural water-soluble tea pigments formed during the processing of fermented tea, possess multiple hydroxyl or phenolic hydroxyl groups within their benzodrol phenol ketone structure, which is one of the determinants of the quality of fermented tea. In recent years, TFs have garnered widespread attention due to their diverse biological activities, including anti-inflammatory, hypoglycemic, prevention of cardiovascular, antiviral, antitumor, antibacterial, protective of mental health, and organ protection effects. As research on TFs continues to deepen, their mechanisms of biological activity and clinical application prospects have been gradually clarified, and they are expected to play a greater role in various fields. This paper reviews the biological activities and mechanisms of action of TFs, as well as their application status and research directions in fields such as biomedicine, food health, beauty and daily necessities, and agriculture and animal husbandry, aiming to provide an outlook for the future development and application prospects of TFs.