The supplementation of livestock rations with herbs containing bioactive components, such as rosmarinic acid (RA), have shown promising results as a natural feed additive in promoting growth, productive and reproductive performance, feed utilization, fertility, anti-oxidant status and immunologic indices. Furthermore, RA reportedly reduces the risks of various animal diseases and mitigates side effects of chemical and synthetic drugs. RA is a natural polyphenol present in several Lamiaceae herbs like Perilla frutescens, and RA is becoming an integral component of animal nutrition as it counters the effect of reactive oxygen species induced in the body as a consequence of different kinds of stressors. Studies have further ascertained the capability of RA to work as an anti-microbial, immunomodulatory, anti-diabetic, anti-allergic, anti-inflammatory, hepato- and renal-protectant agent, as well as to have beneficial effects during skin afflictions. Additionally, RA is favored in meat industries due to enhancing the quality of meat products by reportedly improving shelf-life and imparting desirable flavor. This review describes the beneficial applications and recent findings with RA, including its natural sources, modes of action and various useful applications in safeguarding livestock health as well as important aspects of human health.