Theaflavins (TFs), specific polyphenolic compounds found in tea, including TF, TF-3-G, TF-3'-G, and TFDG, are renowned for their health-promoting effects. The growing interest in TFs among researchers necessitates a comprehensive review of their properties and impacts. This review systematically examines the chemical and physical properties of TFs, covering their isolation, purification, synthesis, safety, and bioavailability, as well as their implications for health. Special attention is paid to the dynamic interactions between TFs and gut microbiota (GM), exploring how GM metabolizes TFs and the consequent effects on the microbial community. An in-depth understanding of these interactions is crucial for realizing the full health benefits of TFs. Additionally, this review summarizes the well-documented health benefits of TFs, including their roles in ameliorating metabolic diseases, exhibiting anti-inflammatory properties, reducing viral infections, and potential applications in treating cancer and neurological diseases. It also explores the potential industrial applications of TFs, underscoring the need for further research to enhance their benefits for human health and well-being. The primary goal of this review is to support and inspire further detailed investigations into TFs.