The thymol is an herbal food additive used to improve performance indices, feed utilization, immune system, and preventing from infectious diseases. Feeding animal, fish and poultry with diets supplemented with medicinal plants containing effective compounds and natural antioxidants in thymol demonstrated valuable potential of thymol to enhance the productive and reproductive performances, nutrient bioavailability, immunity and general health of livestock as well as lowering the problems of different animal diseases, side effects of chemical drugs, syntactic materials and cancer. These properties may be attributed to thymol’s capability to work as antispasmodic, antioxidant, antimicrobial, immunomodulatory, anticancer and anti-inflammatory agent by suppressing harmful compounds/free radicals from interacting with cellular biological compounds, ability to alter the gut microbiota, and increasing digestion, absorption and metabolism of nutrients. This review illustrates the multiple beneficial applications and various aspects of thymol including its chemical structure and physical proprieties, metabolism and excretion, mechanisms of action, natural sources and practical applications in animal, fish and poultry nutrition for increasing production, immunity and safeguarding health.