As a major global producer and consumer of beef and lamb, China’s beef and lamb industry holds a central position in securing meat supply to its population. However, it currently faces challenges such as intensified international competition, high production costs, and rising quality demands; thus, improving meat quality has become a key issue for the industry’s development. Nutritional factors are central to regulating meat quality, and polyphenolic compounds, as natural bioactive substances, have remarkable potential in enhancing the sensory characteristics and nutritional value of beef and lamb. This article reviews the effects and mechanisms of plant-derived polyphenolic compounds on the meat quality of ruminants, focusing on key quality indicators such as color, pH, tenderness, flavor, and water-holding capacity. This review aims to provide a theoretical reference for understanding the mechanism by which polyphenolic compounds regulate meat quality, thereby contributing to the high-quality and efficient development of the beef and lamb industry.