Due to the negative impact of antibiotics on human and animal health, they have been banned in animal breeding and substitutes are being explored. Polyphenols – naturally occurring ”plant secondary metabolites” – are one of the best alternatives. They are found in vegetables, fruits, cereals, herbs, legumes, and spices. The main classes of polyphenols include flavonoids, nonflavonoids, and tannins. Polyphenols have been found to exert highly positive effects on both human and animal health. These compounds have been recorded to exert positive influence on growth performance, immune system, antioxidant system, and meat/carcass quality, as well as antimicrobial effects in poultry species. The objective of the ruminant farming system is to obtain highquality meat and milk and reduce greenhouse gas emissions through improved rumen fermentation and microbial manipulation using phytogenic extracts (polyphenols). Studies have reported that the use of polyphenols in ruminant rations enhances the quality and quantity of meat and meat by-products and reduces the application of synthetic antioxidants and antibiotics, which have been of concern to consumers. Similarly, it has been found that the addition of polyphenols increases oxidative stability, overall acceptability, sensory and nutritional quality, as well as shelf life of meat and its products. However, due to the differences in the chemical composition of 25000 polyphenols identified so far, it is difficult to determine the beneficial effects and optimum dose of all compounds for inclusion in animal and human diets. This review discusses the bioavailability of polyphenols and their growth-promoting, production-enhancing, immuno-modulatory, antibacterial, and antioxidant effects on animals.